My ex best friend and I got along incredible well, went for walks together, we never ran out of things to talk about. During our walks she also told me she is not happy with the bf, he gets drunk, gets into arguments with other people whilst drunk and a few times got beaten up for it, he is not really there when she wants to talk to him about her problems... About 2 years after our friendship started, she confessed that she had feelings for me. She said that she likes spending time with me and how I have ambitions in life etc. I liked her too, so we thought we could give it a go. Since she was still in a relationship, we agreed not to do anything physical until she breaks up with him. She asked me to give her some time though because the boyfriend was unhappy at the time because he had dropped out of college due to poor performance (because he got drunk quite often). We agreed on six months. Six months went by, nothing happened, so I asked about it and she said she needs more time. I said okay because I did not want to pressurise her. After I while I became complacent about the whole situation. We ended up having a full on physical relationship. We also started talking about our future together (house, family etc). I sometimes still asked her when will she break up with the bf, she said she is not sure what to do and she needs more time (massive red flag if I think about it now, but I suppose I did not want to admit it and chose to ignore it). This made me unhappy because I did not want to carry on waiting, but I wasn’t too vocal about it because I did not want to pressurise her. At the same time, I put my ambitions on hold - I declined a few good job offers because these would have meant to I would have moved far away from her, which would have ended the “relationship”. During our last year “together”, things started to go downhill, because I started being a bit more vocal about me being unhappy with the situation, which made her unhappier I suppose. She also asked me to delete all of our messaging history so that he would not find out accidentally and I eventually deleted it without thinking about it too much (but thinking about it now, I am sure she just wanted to delete the evidence of her cheating so that I could not use it against her later on even though we carried on having sex after this). I think reality started to kick in and I also realised I am a massive asshole for doing this to the other guy, so I basically told her she needs to make up her mind and also started saying no when she was trying to make any sexual advances. I think the fact she had to make a decision at one point made her anxious and depressed (just my opinion, because she was not the happy person any more I had known when we first met). I told her perhaps she should talk to a therapist to help organise her mind, but she rejected the idea and told me that she is just more grown up. Shortly after (1 month or so later), she called me and said she is going to stay with her bf because she loves him more (which means that she must have not loved me at all, because who cheats on someone they are that much in love with). She proposed that perhaps we can go back being just friends. I said that is not going to happen (one of the hardest thing a I have had to say but so proud for it now) and that she should come clean to her bf anyway, in order to help with her own mental state and because I was feeling guilty about the whole situation myself as well. She promised she would do that. A few weeks later I heard from a mutual friend, whom I had told the whole story, that they were going to move in together. So I got back in touch with her, did not mention what the friend told me but outright asked her if she told him. She said she told him that we had feelings for each other, but chose not to tell him about the sex or our talks of having a family together. So I told her that she needs to tell him everything, otherwise I will do it. She blamed me for trying to destroy her life but a few hours later texted me she has done it and told me not to contact her ever again. Some time later the mutual friend said that apparently they were going on a trip together. I texted her again (she had not blocked my number) because it felt like he still did not know, then got a text back from her number but it was the bf replying so I told him the whole story but just told me that I need to move on (like wtf, you have every right to hate me, but I was only there to make him aware of the truth, only to learn that he was okay with everything and they were still together). I left it there because that was not my business any more. The mutual friend told her some time later that he is aware of the story to which she responded that the bf and her broke up and are no longer going on the trip together. Then heard a month later from another mutual friend that the bf and her are definitely living together now and went on the trip together.

The worst thing about the whole thing is not that she chose the other guy but that she led me on all these 4 years making me sacrifice some great opportunities, and then going on to lie to me about things even though she knew how important it was for me that she come clean to her bf. I thought I knew her inside out, apparently I did not - I sometimes wonder if the whole friendship was fake too. Nonetheless, good that I got to know her real persona, even though it happened quite late, but still better than never. This has left me with some massive emotional scars and being afraid of forming new relationships with people because I am not sure if they are genuine or not.

Back to the topic: I do believe that some people cheat because they came across someone they have more in common with but things end up progressing very fast so there is some overlap in relationships. But there are definitely some people who are only cheating for their own shellfish reasons. If you are the person you are being cheated with and you love the cheater, it is always easier to ignore the red flags rather than be honest with yourself. However, in the end when the cheater gets bored with you, the truth will hit you hard.