Am I (18f) overthinking or am I right about second guessing my bf's (18m) feelings for me
This is a throw away account, because idk if im overthinking or over reacting, or if I'm right for feeling like a placeholder relationship. So for context me (18F) and, we'll call him E (18M), have been friends since we were about 11 or 12. E has had two girlfriends that I knew about, (1 that I just found out about, but have no other knowledge of), when he was dating the last one, for about two years, he was banned from talking to me by her. When they broke up we got close again. We made a pact in October-ish, temporary date until one of us finds someone, so he'd be my stand in boyfriend. Its now April, we've done birthdays and valentines with each other, we've also slept together frequently and plan to go to prom together this month. Well, at the end of February, I got the dreaded "we need to talk" text. We talked, and he went on a rant about how he really likes me, but he doesn't feel like he can love me woth everything he has because he still loves this girl he met and talked to for a week in August, so we really needed to keep it fwb. After about a day of that, he apologized and we made it official. Well he treats me so well, but its just a little off, because he just followed this girl on Instagram (he just got one) after telling me shes not a problem and he loves me. Well hes replying to her stories and stuff. He also has like... 2 other girls on his Snapchat that ive seen, and he shows me so it doesn't feel like a big deal, but honestly, I don't like it. And I've always been an overthinker, and ive never had a boyfriend before him (sad, I know), so im also a bit insecure, so I don't know if I'm overthinking or if this is a problem. Some context about the girl, she lives out of state, about 12 hours away I'd say, and idk if I'm just a placeholder until he graduates and moves out of his parents house.
Tldr: my boyfriend might still like this girl, and he followed her on Instagram, and im not sure if I should be worried or not