help please, boy problems

so I'm really attached to this guy and I don't know, I'm 17 and we've been on and off 3 times since last July, and IV seen other boys in between but I'm still a virgin! But the guy I'm really attached to I can't seem to loose feelings for him,  but when we get back together it doesn't feel right so I leave him and want him back again after I leave? He was my first kiss though? I don't know what to do please help