My Girlfriend shows interest in other guys on Instagram/Vine.?

[Democritus]

Girls subconsciously do things to test you. She knows you're following her on those sites. Don't let it phase you. Maybe even comment on some girl's picture. And if she brings it up say, "You do it, so I thought it was ok." It doesn't sound like these are guys she knows anyway. She does that to pseudo-famous people. I have to disagree with the people who say to break up with her. If these were guys you know personally, then that would be a different story. Perhaps they did not read the details of your question. It sounds like she has a libido though. I would try to exploit that to your advantage.