When directing character-driven comedies, Stoller noted that the most important thing to remember is that the comedy must come from honest situations if the scene or the dialogue is going to be naturally funny. Forcing comedy, he said, is generally not a good idea.

"It's a lesson that I've learned over the three movies I've done," Stoller explained. "I remember on 'Sarah Marshall,' I was pushing Jason to be broader than he should have been and was trying to hit the joke card. But after Judd Apatow watched dailies, he called me and said, 'You don't have to try so hard. You should direct Jason to just react naturally to the nightmare of his ex-girlfriend showing up at the same hotel he's staying at.'"

Stoller said once he went with the more natural approach, it became "the funniest thing ever."

"The more truthful, the funnier it is, and the more subtle, the better," Stoller said." You just need to show people the way they would really react."

Another part of that natural reaction, Stoller added, is that dialogue should never come out an actor as if it sounds rehearsed. Thankfully, he said, Segel uses a great method for making his lines feel real.

"The more sloppy he makes the dialogue sound, the more realistic it is," Stoller said. "People don't ever have perfect sound bites of things that they say in real life, whether they're in a fight or trying to propose. You're always pretty much working your way through it, so that makes it funnier, I think."

While "The Five-Year Engagement" is at heart a romantic comedy, Stoller is proud of the fact that he and Segel weren't afraid to confront dramatic moments in the script, including the spats real-life engaged couples have as their relationships deepen.

Ultimately, Stoller knows, that if "The Five-Year Engagement" turns from comedy to dramedy at some points, the film will only benefit from it because the situations become all the more relatable to its audiences.

At the same time, he said, its important pull a scene back before it becomes complete drudgery.

"We really tread the line on this one -- it's probably the most dramatic of the three movies I've directed," Stoller observed. "But I think it's very interesting when we have a scene that goes there, like the bedroom argument scene. There has been an explosion of laughter from audiences when he wants to be alone and she starts to leave and he says, 'I just want to be alone with you here now.' It's a funny line and its great relief for that moment."