i was at my gf's house the other day, fixing some things for her. someone called her and i heard a male voice. i know that she has male friends, and even though i dissaprove (i'm EXTREMELY jealous), i understand that she is just friends with them, and i don't really mind if she spends time with them while i'm not there. but this time it felt weird -- as soon as she knew who was on the phone, she ran into the other room. i was surprised by her reaction, so i followed her into the room. as soon as she saw me walk into the room, she quickly hung up. i asked her what's up? she said it was this guy who she met while we weren't together (we broke up for around 3 months then got back together) and that he's just calling to see if she wants to play cards on wednesday night (this was monday). apparently, she tells me that she's been seeing this guy every so often, apparently just to hang out. i was very upset, because usually she tells me if she's going to spend time with other guy friends, but this guy she kept in secret from me. what do you think about this? is she cheating on me or not?