Big things are happening on The Big Bang Theory's Season 8 finale.

How big? Jaws-on-the-floor big, according to executive producer Steven Molaro. "I think there will be a few jaws that are no longer closed and won't be for a while," Molaro tells TVGuide.com. "I'm not just saying that because I'm on the show, but I would feel this way if I were a just a fan. The jaws will be very open."

Finale preview: Scoop on your favorite shows

Thursday's finale (8/7c, CBS) will be all about the show's four couples as they navigate different stages of their relationships and consider the future — that is, if they can even picture one together. So, what's next for each of them? Find out below!

Sheldon (Jim Parsons) and Amy (Mayim Bialik)
The finale marks the fifth anniversary of the first time the pair met, but the milestone only serves as a reminder for Amy at how tortoise-like their relationship has evolved since that fateful day. Lest we forget, they had their first kiss last season and said "I love you" for the first time earlier this season. "While things have been progressing with that relationship, it's still been glacially slow and Amy has just about had enough of it," Molaro says. "Amy is putting the screws to Sheldon for more. She feels like she's been patient long enough."

But will that pressure just scare Sheldon away? Molaro assures that we don't have to worry about Sheldon taking off again like he did last season finale when he had a crisis of confidence over his career. Instead, he'll take Amy's concerns to heart and turn to the only longtime couple he knows for advice. Well, it's less advice and more like an interrogation. "He goes to Penny and Leonard ... because they still don't have a wedding date yet," Molaro says. "Why are they delaying that if they're supposed to be a couple that's progressing? That's his logic and it's pretty sound."

So will Sheldon actually give Amy what she wants or keep things status quo - or at least come to a compromise? "I will say that Sheldon won't dismiss Amy's concerns," Molaro teases. "All four [Sheldon, Amy, Penny and Leonard] make life-changing and series-changing decisions about their relationships in this episode. It's an emotional cliff-hanger."

Penny (Kaley Cuoco-Sweeting) and Leonard (Johnny Galecki)
The couple will be "greatly" affected by Sheldon's line of questioning. "Sheldon points out some legitimate things that they haven't really thought about and it really makes them take stock of where they're at," Molaro says. "Why haven't they set a date yet? Is it really because of work? Or are deeper issues at play here? On the other hand, does it matter when they get married as long as they're happy and committed to each other?"

One thing's for sure: Penny and Leonard will be compelled to do something to take the next step. That "life-changing" decision could be walking down the aisle, but Molaro warns that that there are more twists to their "big move." "They find themselves in an interesting place that you'll definitely want to watch the [Season 9] premiere."

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Raj (Kunal Nayyar) and Emily (Laura Spencer)
Looks like Emily is too much strange for Raj to handle. The opposites-attract pair might be too different to last — in Raj's mind at least. "He's started to realize in his heart that maybe they're just not the right match for each other," Molaro says. "She's into weird, dark stuff. There's a very dark side to her. Her interest in the macabre is starting to freak him out a little bit."

Wanting to break up with someone is a whole other ballgame than actually doing the deed... especially since Raj's biggest split was probably with Siri. "You're talking about a guy who's in a relationship with a pretty girl but has not actually broken up and ended a relationship on his own in his life," Molaro says. "Can he actually do it?" But maybe the bigger question is: Should he go through with it? "You can argue that Emily being weirder than any other girl he's known or dated is good for him and if there's still an attraction there, why break up?" Molaro says. "Maybe he should give this more of a shot."

Howard (Simon Helberg) and Bernadette (Melissa Rauch)
Don't worry — these two aren't getting a divorce or considering having kids yet. That's because they have to deal with their surrogate son, so to speak, Stuart (Kevin Sussman) still living in Mrs. Wolowitz's house. "It's the opposite of empty nest syndrome. They realize that they may have had their fill of Stuart living in their house and want to kick him out," Molaro says. Like with Raj dumping Emily, though, can they go through with it? "They're not afraid of doing it, but obstacles will be in the way and they have to figure it out," he says. "Bernadette is pretty clear that they can't move on with their lives with him still living there. All of these issues are being confronted in this episode."

He continues: "I really think this is one of the best episodes we've done. I think there'll be a range of emotions. You'll see that it is so powerful that the jumping-off points [for next season] will be pretty apparent. You really don't wanna miss it. Am I selling this enough?"

The Big Bang Theory airs Thursdays at 8/7c on CBS. Watch a sneak peek of the finale below.

(Full disclosure: TVGuide.com is owned by CBS.)