My bf kinda cheated on me he's 20 and I'm 16. This girl is 18 but I think she doesn't know about me because my bf never posts anything about me. He said they're just friends but they talk to each other everyday. I told him to post a picture of us (me kissing his cheeks) but he always delays it and never want to post it.

Is it possible that he would leave me for this girl or will he come back to me when he's done with her because I'm his main gf? Or should I tell her? He knew me first and dated me first. I love him so much.