I keep getting too attached

i’ve (f19) been in an on and off situationship (m19) for the past 3-4 months. We met thru a dating app and pretty much hit it off instantly. we study in different countries but come back to the same area during vacation. We got super close (calling everyday, texting etc) and stopped talking to other people. but there’s a lot of issues i see in our relationship that makes it on and off. we tend to argue a lot; he’s very stern and hates when i give him my insight that he doesn’t like. he also has this problem of joking about stuff i don’t really find funny like my weight etc. we’ve met once and it was really fun but after that he got “busy”. he mentioned that we’re dating and he doesn’t see the appeal in asking me to be his gf. i tried multiple times to meet up with him but he was always busy. at the end we decided to end things and he apologized on how busy he’s got. We rekindled about a month later while both of us are on vacation and really hit it off. however we still go thru the fights (he blocked me once). I’ve realised that he’s bipolar with me all the time. I’m very confused because i keep wanting to be with him even tho he always treats me really bad and says stuff i don’t like. i keep losing my mind when i send him stuff and he doesn’t reply after a while (he would be active and then suddenly disappear, or one day he would be super happy and loving and one day he’ll absolutely hate me). He’s giving me no reassurance on anything to a point where we don’t even talk about our days we just keep sending each other reels. there are so many other men who i’ve encountered who was the absolute sweetest but i keep going back to him. what do i do? i don’t understand why im so attached to a point where my mood for the day depends on him.