help! i’m kinda confused.

so i know i’m not straight, for sure. but i’m kinda confused, in terms of relationships. i’ve been in multiple relationships, most of which are with guys, however, with any relationship i’ve been in with a guy, even if i’ve has a crush on them for years, i loose interest within days of dating them. but with girls, i either dont loose interest at all and we break up due to personal issues or i loose interest very slowly. the other thing is, i tend to not really have full blown crushes on girls as much as i do with guys, but i have the urge to have some kind of SO. any advice?