A movie with different stories around a party. There’s a pool and lost engagement ring

I can only remember pieces of the movie. I have no idea whose in it. It’s not project x and it’s not a thriller.
There’s a girl whose ”friends” plan on being roommates behind her back. Said girl is an Uber/Lyft driver. She drops a guy off at the party and he leaves his phone in her car.

There’s a man and woman that attend the party, the man wants to propose to his gf but loses his ring at the party. I believe in the pool where he does eventually jump in (the host is angry he gets in the pool and wants to fight him)
At some point the lights go off at the party (in the backyard) I believe someone tripped over the plug in to the string lights?

Please help me