<human>: Okay so, me and my SO have been together for just over 4 years, we use to be really close, talk about anything and everything with each other. Now he has found another girl to be best buds with and I'm afraid its gone further than that.. talking with each other all through the day, sending each other selfies regularly, i have told him how i feel about this and he says if i can't stop being jealous then he will break-up with me because he feels "like having a gun to my head every time i talk to her" he tells me that he doesn't find her attractive in anyway and doesn't have feelings for her, but i honestly can't believe that.

I know I'm going to hell for this but i went on his facebook and saw some concerning things in their chat- one about a selfie and my SO saying to her "what if [Me] was sitting next to me be careful" and one where he was warning her to not to talk to my friend as they tell my everything. Also caught some light/playful flirting in there. He said when he met her he just wanted to get to know everything about her.

Not sure whether those are red flags or not? i feel that he does love me but he likes her. confused/worried.

Condense the text into a few key points
<bot>: SO sending selfies and being really close with another girl, can't be jealous of their friendship or its over but feel like its more than friends.