annoyed with my BF !!!

I'm in a relationship with my parter for years now , he's 21 and I'm 26. 
When we weren't a couple i was the one in love with him , always thinking about him , and always got butterflies in my stomach everything we hung out but he didn't feel the same way I did ,(so I thought)  then after we started going out he was the one who was all lovey dovey and madly in love with me , acting jealous and what not... But after years gone by im just starting to get over him , hes super attractive but acts like a little boy & he's kinda immature in some way but he's 100% independent ! I love that he's super affectionate, always kissing me , holding my had , slapping my butt and grabbing my boobs randomly & he's such a horn doggy ;) but just not romantic :( I don't know what's  making me feel like I'm over him , even the little dumb things he do makes me crazy !!! Sometimes I just feel like walking away ...