The film firmly averting the third-act break-up. Mac and Kelly have a fight and she storms off with Stella, but she comes back the very next scene and they apologize to one another. The whole situation may be stressful, but at no point is their marriage in danger.
Teddy taking the fall for the final party and sending Pete away so he won't get in trouble and ruin his future. Their escalating I love yous take it into Funny territory but it's still sweet, they're both tearing up.
Mac and Teddy making amends in the end.
When Mac and Kelly bribe a pledge, Assjuice, into pushing back against Delta Psi's hazing rituals, Teddy takes him aside to ask him if everything is okay, completely ruining their scheme by being too nice of a guy.
The first party the Radnors attend, before everything goes awry. Teddy and Mac bond over Batman, everyone coos over Stella and how cute she is, and Kelly's story about how she and Mac met to a group of sorority girls gets a huge "Awwww!" from everyone.
The Sequel
Sometime between the first and second film, Pete came out of the closet. Teddy, Scoonie, and Garf have no problem with it and even help Pete's boyfriend propose to him in the beginning of the film. Even better, the proposal features them singing Pete and his boyfriend's song, "I'm Yours."
When all the Kappa begin to cry because they think they'll lose their friendship without the sorority, Kelly (with help from Mac and Teddy), talks to them and helps them realize that they don't need the house to stay friends with each other.
The Kappas thanking the Radners for their advice by renting their house from them to give the overflowing pledges a place to stay.
