Why would a guy friend share his very personal thoughts with you?

He trusts you.
He is relaxed with you.
You are soothing.
He hopes to make you fall in love with him.
Any of the above possible reasons.

It's a thing called "sex".

He probably just feels really comfortable revealing such personal things, and he also trusts you as well.

Assuming he's straight...

* You're a close guy friend.
* He's drunk.
* He's high.
* You're a girl in the friend zone.
* You're a girl he doesn't really care about, but he knows you're into him enough to listen, so telling you lets him get it off his chest risk-free, and it probably won't turn you off because of how into him you are, but if it does make you not like him anymore, then bonus, because he's finally freed himself of an annoying cling-on.

If he's horny and you're doable, he's not sharing his very personal thoughts with you. Maybe he's sharing what seem like very personal thoughts, but what he's saying is really just a bunch of BS he's making up hoping it'll make you all mushy so that maybe you'll let him play with your boobies.

bored. friend zoned. etc.

Maybe because he likes you or feels comfortable telling you?