It's difficult to even find a title for this post. I (m46) started into the world of enm/poly last year. I am happily married and after many discussions with my wife, I started dating someone (f36). She and I fell in love and it was amazing. She and my wife were friends. We had an incredible connection and I was more happy and fulfilled than I ever had been in my life. Cut to, after over a year of dating I found out that my girlfriend had sex with a friend of hers and never told me. I initially found out because her friend told a mutual friend of ours. After many conversations my girlfriend finally spilled the beans. I am devastated. It happened more than a month before I found out. She said she never told me because it happened very fast and was afraid I would leave her. She and I have had numerous conversations about dating others and I always supported her seeing anyone she wanted. All I asked for was communication. That's why all of this is such a shock. I am so sad and very disillusioned with poly/ enm now. She has said many times that she knows that she broke the golden rule of this lifestyle by not disclosing this. I miss her so much and I don't think I can trust her moving forward. I don't know if I am looking for advice? Insight? I am just so sad. I have tried to ask what I could have done to make telling me easier for her. She has stated several times that I did nothing wrong. Simply that she made a huge mistake. Any thoughts are welcome.