is this worth it?

So I've been talking to my boyfriend for six months and then a drunken night recently, I decided to make it official to catch him off guard and it was all fine and dandy. He's currently grounded(we are 16&17) and i went on his snapchat to do his streaks (which he allows me to do). He was at camp for like a week and was able to do them himself but when hes at home he cant, anyways, so i went on there to see a new girl, and shes his number one. it sounds stupid but it bothered me, bc he has a past of talking to other women while hes with someone and did it to me when we first started talked but i gave him another chance bc i really liked him, and hes been great till now. I didn't see any messages besides the thread of back and fourth snapchatting and i asked him and he said shes an old friend & comes to find out she was at the camp. He says i have nothing to worry about but is becoming very distant and although he can't talk all day he usually talks to me all night and now just says goodnight and thats it. it sounds stupid, but its sketching me out and i dont want to waste my time anymore, if its not worth it. is this worth saving? what should I do?