Hi. So I need help to rationalise my situation. I don't have friends that I can talk to about this. It's a very long story so I apologise and it's something that's been a weight on my shoulders for around 4 months now. Me and my girlfriend have been together for 15 months and everything was going great until she started a new job and started working with a girl who is also gay (girl A). Things started to change when girl A left her girlfriend of 4 years and started messaging my girlfriend constantly, literraly from the moment she opened her eyes in the morning to the minute she shut them at night and would also phone her very late at Night. I began to become suspicious of something but didn't say anything because I trust my girlfriend, however they started texting through Snapchat which I thought was odd since she never liked Snapchat and always uses messenger. My girlfriend then started meeting this girl outside work and would tell me that girl A was coming over to her house at 10pm to watch a movie and she would stay there until 1/2 in the morning. I began to get really suspicious and anxious that something was going on between them we I confronted my girlfriend and she reassured me that they were just really good friends. So after 3 months I was still paranoid that something was happening between them, they were meeting up more often for dinner and she was now going to her house late at night and my girlfriend was beginning to hide her phone screen from me when she received a Snapchat message from girl A, so one morning I couldn't handle it anymore and I decided to check my girlfriend's phone and I found messages saved on her Snapchat from this girl A. Girl A had sent my girlfriend a message stating that she was so madly in love with my girlfriend and that she was gonna do everything she could to win her and that she gonna ask her into her bed anymore she was just going to let it happen when the time was right for my girlfriend. She then went on to say that she was going to protect her and give her everything inlife that she deserves and blah blah blah a bunch of other stuff. I immediately broke down in tears and confronted my girlfriend, my girlfriend's response was that I shouldn't have been snooping on her phone and that if I trusted her it wouldn't be a problem because she's in a relationship with me and not her. I asked my girlfriend to choose me or Girl A and my girlfriend told me she wasn't choosing anyone and i would just need to trust my girlfriend that nothing happening. So that all happens about 2 months ago and I can't stop thinking about it. My girlfriend still talks to this girl constantly and even meets up with this girl behind my back. I saw a message on my girlfriend's phone from Girl A. Girl A is still telling my girlfriend that she loves her and that she's going to treat her right and buy her things and take her different places and give her what she wants and deserves. I just don't know what to do. My girlfriend says that she's just a stupid girl that doesn't really love her and that if I trusted my girlfriend I shouldn't have anything to worry about and that they are just friends. I just need someone to help me with this who has been in a similar situation. Do I leave my girlfriend or do I trust her that there's nothing going on between them.