While Penny did her best to overlook the fact that Leonard had kissed another girl two years ago while he was on his North Sea expedition, she was unable to get past it and thought of the girl — who, it turns out, works at the university with Leonard. The fact that Leonard sees Mandy (Melissa Tang) regularly also doesn't sit well with Penny, and their wedding night is ruined. The duo head home to Pasadena, where they spend their first night as husband and wife in their respective apartments. (Also not helping matters is Sheldon confirming that Mandy is "brilliant and attractive.")

Sheldon (Jim Parsons), meanwhile, can't give Amy (Mayim Bialik) the space she needs and winds up pushing her to the brink of finalizing their breakup. He turns to his mother in Texas for support and viewers learn that the ring he had planned to give Amy when he proposed belongs to his great-grandmother, illustrating that, in his own way, he really does care.

Here, The Hollywood Reporter chats with leading man Galecki and showrunner Steve Molaro about the wedding, the fight and, yes, the Roommate Agreement that may or may not keep the newlyweds from officially moving in together:

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The wedding has been eight seasons in the making. What was being on set for that scene like?

Steve Molaro: It was great. It's a rocky episode for them but I wanted to make sure that the actual wedding moment was satisfying, sweet and lovely, which I think it was. We were all pretty happy with how it turned out — especially with Penny's vows. Kaley did a great job with them. I was so excited about that scene and she came through and more.

Johnny Galecki: It was emotional. I love both of these characters, as Kaley does, and we're very protective of them. We're their biggest fans and we've been rooting for them for a long time and it was time to pull the trigger after talking about it for so long.

When you first heard that Leonard and Penny were actually going to go through with it, were you surprised?

Galecki: No, I wasn't surprised. We talked about it [with the writers] that they may or may not take that step. What we didn't want to do was play up the will-they-or-won't-they any longer. It wasn't in the audience's best interest. The audience wants to see them married. But just because they have rings on their fingers doesn't mean that it's solved every relationship problem. Marriage doesn't answer all the questions and doesn't solve all the problems. So there will be plenty ahead with this commitment that they share. There's very little comedy in everything working out well (laughs), so we'll see what happens in the future. But we didn't want to dangle the marriage carrot over the audience's head any longer.

Will there be any sort of formal reception?

Molaro: There are no plans as of yet. The guys all got to see it on the Internet and that's good enough for now. I feel like an actual wedding happened.

How will Penny's father, Wyatt (Keith Carradine), respond to Leonard as a son-in-law? What kind of fatherly advice could he have for Penny?

Molaro: We see him again in the third episode and we'll see Penny talk to him and let her father know what's going on there. Leonard doesn't cross paths with Penny's dad in this episode, but we'd love to have him back down the line. The vibe between Wyatt and Leonard is fantastic. The marriage is all so new to him; we don't dig too much into fatherly advice yet. You'll have to see how it all plays out.

What about Leonard's mother? Will she have any non-therapist advice for her son?

Molaro: We don't happen to see that occur on the show. I'm sure it happened but I don't know exactly what happened.

Will Penny legally change her last name? Will we learn what her maiden name was?

Molaro: I hope not! I'm still afraid to know what it is! (Laughs.) We've made it so far without knowing, I think we have to go all the way to the end. She has taken his name and maybe that's convenient so we don't have to deal with her maiden name, but she is Penny Hofstadter now.

Leonard's vows are very special and include a nod to the theme song. What went into writing those?

Molaro: We wrote it as a group in the room. It's funny, the [live] audience giggled a little bit the first time they heard them because they thought, maybe, they were going to be goofier than they were, but then very quickly, they caught up and realized it was beautiful. We talked about it and wanted his vows to be very Leonard-like and sweet and evoke some kind of science and Penny's vows to be off the cuff. We had the idea for her quoting the Toy Story song for a while. We had that part before we knew what Leonard's vows were going to be.

Galecki: I was glad they were written on a card I was holding in the scene because I was very emotional! It was very much within Leonard's language. I've always loved those episodes where she might not be able to relate and certainly doesn't have the same passion for physics that Leonard has but she loves his passion for it and that's appealing to her. It was nice to hear the live audience giggle when he launched into his vows being physics heavy and then ending in a very emotional and honest, genuine place.

What made Toy Story's "You've Got a Friend in Me" right?

Molaro: It seemed to be the right blend of silly and fun and something she could believably pull out of her head at the last second that also when it was done being silly, actually did mean a lot to him. She knows him and knows that Toy Story is one of his favorite movies. So while the words aren't exactly the most romantic, the sentiment of all of it is.

Galecki: That's been something the writers have enjoyed a few times. In the first episode we discussed Leonard's love for Toy Story. There's also a funeral scene when Bob Newhart's character passed.

Will either Leonard or Penny have any regrets about eloping? Especially given the nature of what they come home to?

Molaro: They come back and there's certainly some level of regret in that walk up the stairs. They're more worried that they're not sure how to fix it. I don't know if it's regret yet. They're still hopeful it can be fixed, they're just not sure how. I'm always hopeful for Leonard and Penny, without a doubt — and for all of them. I want all seven of them in this world to be OK.

Galecki: I was surprised the whole group wasn't there. We'd done that with Howard and Bernadette's wedding, so I understand why the writers chose to make it different. But at this point in Leonard and Penny's relationship, it's just let's take the plunge already. In true Leonard form, he was a little too honest [with Mandy]. Leonard can fit a whole boot in his mouth most of the time and he was honest with her in a way that I find equally admirable and idiotic. He's happy she's still speaking to him, as he should be!

The fact that Leonard is taking responsibility for this fight shows a lot of growth for the character. It's a very grown-up thing to say.

Molaro: It could have all been avoided. It's nice to get to see all these characters continue to grow and deal with life and what it has in store for them.

Galecki: When you get a role you love you want to run with it. Early on, [co-creator] Chuck Lorre always said, "Let's be patient. We understand your passion for this role and you want to evolve the character but these guys evolve slowly, think of molasses in terms of evolving." There have been moments where if we didn't mature the characters — like when Leonard told Penny he was in love with her and she didn't return the sentiment — that changes a person. It would be irresponsible to not then change the character a bit. There are those opportunities to do so. Taking accountability is a big step for anybody and it's often not easy.

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Now that Leonard and Penny are married, how will they tackle the Mandy flap? Leonard didn't expect to spend his wedding night with Sheldon.

Molaro: I do feel somehow in the context of this show, Leonard should be with Sheldon for some reason on his wedding night. It seemed oddly OK to me — and the way it should be. (Laughs.) But moving forward, we're flying right to the face of it in the second episode in meeting Mandy and Leonard working hard to try and put this behind them.

How awkward will Leonard's and Penny's interaction with Mandy be?

Molaro: That was news to Penny. It's pretty awkward, it's not well advised that he talk to her. But he feels that he doesn't have many options left. So he's really grasping at straws. Ultimately, with or without Mandy in the picture, this will come down to Leonard and Penny and [a question of] is their relationship strong enough to get past a thing like this or not. In the end, it will come down to them and them figuring it out on their own. But I think there's a good chance.

Galecki: There's part of me that's been on the fence about this situation and you try not to ever judge your character but when you're so close to him, it's hard not to. There are moments when I want to defend Leonard. They were not together at the time and it was a kiss. It was influenced chemicals! (Laughs.) It can certainly be worse! At the same time, that Penny is hurt over the whole thing, it's hard to not judge him harshly. As far as Mandy, Leonard is doing his best to rectify what he's tarnished and is going to put his head on the chopping block for Penny for the relationship.

Now that they're married, how do you think things will change, overall, for Leonard and Penny?

Molaro: The biggest hurdle after Mandy is to tackle living arrangements. Sheldon is obviously a big part of that and now that they're married, what happens next is looming.

Galecki: I'm not sure. I've never been married. Part of our job is to hold a mirror up to the audience and be frank and honest and share our human flaws that we all have. There's a lot of hardship ahead.

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How big of a role will the Roommate Agreement come into play in all this? Sheldon can't be happy about this. He hates change and this is a big one.

Molaro: A lot. The Roommate Agreement will be around and out and on the table and being discussed in the fourth episode. Sheldon is not happy about a lot of things that are going on in his life right now. But he's doing his best to try and hold it together and get past it all: Rise above it or solve it. It's a lot of weird things that he knows he's a smart guy and he's used to being able to apply logic and science to figuring things out and none of that seems to be working for him these days.

Galecki: It'll be slow in figuring out [what happens with their living arrangements], both within the story and outside of the story. That's always been the biggest question mark when we've talked about Leonard and Penny getting married: What happens to the two boys? But at the same point, this deep into season nine, they basically all live together; there just happens to be a hallway between their two apartment doors so I don't know that that much will change immediately.

Sheldon isn't ready to live by himself yet — especially in the wake of his split with Amy. But at te same time, Howard and Bernadette have this guy — Stuart (Kevin Sussman) — whom they can't get rid of....

Molaro: Sheldon is very fragile right now. Leonard and Penny — and Wolowitz and Bernadette — both have these men in their lives (laughs), which is a pretty funny parallel that's going on right now. We put all that stuff down and episode three is pretty light-hearted and is a belated bachelor party. And then we go right into working on tackling the living arrangements.

If you were going to pick Sheldon's next roommate, who would you pick?

Galecki: Stuart is pitch perfect! I'm a huge fan of his and I want him in every episode. Because all the guys now are in relationships, we get to have Kevin on more to represent the bachelor character. We certainly can't have those jokes anymore, the audience cares too much about the relationships of Howard and Bernadette, for example, so Howard can't have those risque lines of dialogue and they're too protective of their relationship.

The last time Sheldon was in this kind of situation, he left town on a train. How bad will his freak-out be, comparatively speaking?

Molaro: A freak-out is looming. There's a form of departure — though it's not physical. It's vaguely based in time travel. (Laughs.) I'll leave you with that!

Are you any closer to bringing Bob Newhart's Professor Proton back?

Molaro: We'd love to but there are no concrete plans. He knows he's welcome here. If we can come up with a plan that works with his schedule, we'd love to make it happen. But there's nothing on the books yet.

Sheldon needs Leonard more now than ever given his split with Amy. How will he be a factor as Leonard and Penny look to start life together as newlyweds?

Molaro: Sheldon is dealing with a lot of emotions and they fluctuate all day long between sad and lonely to angry and hurt to jealous. He's not doing a good job of controlling them. It's going to be a fascinating journey to watch him be on, but it's a good one for him and for Leonard and Penny as people. If Penny and Leonard are ultimately going to make it work, something like this will help them, as a couple, be stronger if they can weather it now.

This is really Sheldon's and Amy's first huge fight. Should they find their way back together, could make-up coitus be something you've been considering?

Molaro: They are so far away from repairing it, it's too soon for me to even think about that part. But there's always that dangling sexual issue between them, so if they do manage to get through this, that's not going to go away.

Will Amy explore being single or is she really going to lean on her friends?

Molaro: Amy is definitely going to lean on everybody in the first several episodes. She's not in a rush; she wasn't looking to be with another person — she just wanted to figure out what she's doing and if a full life of Sheldon is exactly what's right for her. Other men aren't really on the immediate horizon for her.

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What about for Sheldon, will he try and make Amy jealous by dating other people?

Molaro: He may try to but that's all it is for him right now: just trying to make her jealous or do anything to get her to have a feeling or miss him. It's all up for grabs for him, what ever could possibly make this stop and let it go back to what it was — that's all he's interested in.

The ring was his great-grandmother's. Will we learn more about the conversation between Sheldon and his mother that led to him getting the ring? That's a huge leap for that character.

Molaro: We don't know exactly what happened there. She might have said, "I've got your great-grandmother's ring, I want to send it to you." I'm not sure how that conversation went down, whether Sheldon asked for it or if she just gave it to him and that's what put the thoughts in his head. Either way, he had been thinking about it. Down the line, the ring certainly is a fixture. It's in the apartment and things will happen with it.

Any update on storylines for Raj as well as Howard and Bernadette?

Molaro: There are lots of fun little storylines going on for Howard, Bernadette and Raj, but nothing causing huge shifts.

See the original story at The Hollywood Reporter's website.

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