boyfriends and breasts

so this past weekend my boyfriend and I were making out and I usually let him touch my boobs with my bra (I put his hands there first) on but this past weekend he asked me if I wanted him to put his hands inside my bra and because I wasn't opposed to it, I let him. after awhile I ended up taking off my bra completely for the first time in front of him. (and this was all consensual) We have been dating for 8 months now and I dont regret it at all but the only question I really have is, why are guys so attracted to breasts?