chest fetish?

Renee • Just a girl in love.
So, I have a thing for my boyfriends chest.... "man boobs" whatever you what to call them. I'm always touching them subconsciously when he's holding my waist or grabbing my butt.
Just yesterday we were laying on my bed and I was on top of him, I reached over and started biting and  kissing his nipples softly. He's always been weird about me doing those type of things to his chest. He tells me it feels "weird". And so just yesterday when I was doing that he said it felt tingly which I thought was interesting lol.
I mean what I want to know is, is there a way to stimulate that area on a guy? At least slowly making him used to it and start to like it? I know I can't make him.
My boyfriend has an ass fetish and I tolerate when he stimulates me back there but I slowly started to like it.