Boyfriend ..help

Lately my bf and I haven’t hung out as much as I would like which I hate. Sometimes I feel like I always want him to be with me. He’s got a job and balances it with school, and friends and me but lately we haven’t been together and Yesterday we were together for like 3 hours, I helped him study for his exam, he came over and he ate, and we did Sexual things .. and then he left me bc he said he was gonna hang out with his friends .. a boy and two girls . So I told him that we haven’t been Together for much and he tells me this .. what should I do and he said he’d give me more time but thennnnn yesterday after he left I logged onto his Snapchat and I saw a snap message from a girl (his friend) that said “sorry for ruining your night i didn’t mean to” and I don’t wanna think the worst but I can’t help it what should I do, am I too obsessed ?? Should I back off ? Like that’s kind of weird