Looking for a story

I’m looking for two stories

One is about someone makes a bet with a friend because his girlfriend who I think is named M (something) left him so he can’t get a promotion because it doesn’t look like he is settling down. His friend has to pretend to be her in front of his boss I think it was on Crystal story site and the male character might be named John.

The other one is a body swap where a young male student maybe a musician swaps bodies in the middle of the night with his teacher who is having sex with her husband and ends up being a better mom.