I think my girlfriend is cheating on me what should I do?
well if you know for sure that she is, then bring it up to her and see what she has to say. if you know she's lying, them clearly she isn't loyal. but if you're not sure and you just assume, then try talking to her before jumping to conclusions because if she's not, then that might really piss her off and you could possibly ruin your relationship. yanno?