having sexuality issues :(

So i have a boyfriend but for some reason when he’s fucking me sometimes I’m not that horny but when I start to think about a girl or girls I get super turned on, I am bisexual by the way and knew at a very young age that I liked girls, and I know I love my boyfriend but it just feels like something is missing and he definitely doesn’t want a threesome which is weird cuz what guy doesn’t want a threesome you know? On top of that he doesn’t really eat me out so maybe I’m just sexually frustrated? I’m just super confused