I've been seeing a guy since February. On our last date he said he was going away the following weekend. I asked who with and he said "a friend". I felt a weird jealous pang in my gut but put it down to BPD feelings of "why don't you want to go on holiday with me" etc. Later on he said he had sent his "friends" (plural) a list of places he wanted to go in that city and I thought it was odd he'd changed from singular to plural but didn't question it. 

Anyway, I still felt weird at the weekend, so I did some snooping on instagram and found a woman who he follows who posted him on their story. In my eyes it's quite a coupley photo/post. I screen shotted it but I feel I can't mention it because I'll look "crazy" and if it is innocent, potentially lose him.

I just don't know what to do. I'm thinking of asking him when he's back for more details on what kind of friend he went with, but if he lies I'm going to find it really hard to not flip.