I want to ask my gf to tell me when she's talking with someone else on social media
Why does she need to tell you everytime she talks to someone else?
Because I'm worried that she's going to have a affair
I think that there needs to be some level of trust between you two. You should not have to know everything that is happening on their social media.
But I'm her boyfriend.
It doesn't matter, she's allowed to talk to whoever she wants as long as she's not cheating on you. You should just trust her more.