My bf and cousin

Hey guys, so I’m having a bit of a hard time today with my unusual situation...

So in May of this year, my current boyfriend and I weren’t officially dating. He hadn’t asked me to be his girlfriend but we had been talking for a whileeee. However, I asked for a break because he wouldn’t ask me to be his girlfriend, so I assumed that he didn’t wanna be with me THAT bad if he hadn’t asked me. With this being said, I have him the chance to prove himself to me. So after 2 months of not seeing each other at all, I invited him over to my house (to help me paint something for school). It was originally just going to be us but then my aunt said she was in town (with my cousins) and that she wanted to visit us. Long story short, he met my cousin (she’s a year older than him) and he basically told me that he was interested in her....yeah, I know. It always gnaws at me but last night my cousin showed me that he requested to follow her (the follow request was from even before May) and it got to me. I just don’t understand why he would want to follow her...or maybe I do but don’t want to admit it. Lol anyway tell me what you guys think about my situation. It’s been a while since it happened, I know. But this is my boyfriend and my cousin we’re talking about