Hello there.
I would like to find some yaoi that's got:

• a more mature feel, by mature I don't mean by lots of sex, but more like feelings and stuff.
• equal standing couples (they have similar social status, similar body build, similar beauty level, etc.) .
• uke and seme who are more adult-like, they keep their composure, they don't overreact, they dont fret for every little thing that happens.
• perspective view in the uke's.
• cheating uke, or both are cheating.
• preferably an ending where they don't end up with each other.

Please help me. Thanks in advance.

You want to read MIYAMOTO Kano. Just about anything she writes fits your request, except sometimes her characters do actually end up together.

Name of Love is a good place to start. Then you could get into some of her longer works:

Moony - Oukaryou Trilogy

Hydra, Rules, and multiple related stories

Angelic Conversation and other "Walker" stories