My fiancé and I (I’ll call him Thomas) have been together for almost 8 years, engaged for a year and a half. Last December, Thomas asked if we could have an open relationship. I was very nervous about this idea but I decided to say yes for a couple of reasons, 1) I want him to be happy over anything else and 2) We hadn’t experienced anyone except each other sexually and frankly I was a bit curious myself. We made a list of agreements that we would follow for this open relationship, the most important ones being that we put each other first in the end and that we communicate everything. Up until this past October, my fiancé had met with I think two other women, just a small hookup with no strings attached. I had chatted with a guy back and forth with some playful flirting, but nothing beyond that. However, in early October, Thomas met a girl through Tinder, I’ll call her Rebecca. Thomas asked to meet up with Rebecca just like the first two girls, and I said yes thinking it would be another simple hookup. However, over the next couple weeks, he asked to go meet her several times, even making the 90 minute trip to Rebecca’s house to hang out. This very quickly developed into a second relationship for Thomas. Asking to stay the night at her place almost every weekend, even staying there for 2-3 days occasionally. Thomas’ phone started constantly buzzing with messages from Rebecca, and I noticed him being in his phone more and more. I expressed to him that this relationship was moving very fast and it was making me feel uncomfortable. He would usually give an “I’m sorry” or brush it off saying he couldn’t talk because he was at work. If I would bring it up in person, Thomas would kind of sit in silence while I expressed my feelings, and he would respond with something like “I don’t know what you want me to say.” I’ve tried my best to keep the peace because I want him to be happy, but then he started changing rapidly. Thomas was seeing Rebecca more and more, he stopped saying “I love you” back, stopped giving compliments, we stopped going on dates. He took it as far as to asking me to cancel our wedding date we had set. Eventually explaining that he apparently never wanted marriage, that we can be together without being married. Thomas even claimed that he is unsure about having kids now, something we have both wanted throughout the entirety of our relationship. At this point, I’ve started to spiral. I let Thomas know every time he leaves to see Rebecca how uncomfortable I feel, and how unloved I feel at this point. I can see the guilt on his face or in his responses over text, but he is choosing every time to not talk about it or will say that he should probably leave me alone if what he is doing bothers me so much. I’ve been experiencing depressive and anxiety symptoms due to constantly wondering why my fiancé suddenly needs a 2nd relationship to be happy. We have a lease that ends early February 2027, and Thomas has told both me and Rebecca that he is unsure if he wants to sign another lease with me once this one ends. I am making this post now because I overheard Thomas FaceTiming Rebecca in the shower, where he stated that he could probably save up enough to pay out his lease early so he can leave as soon as he wanted to. He’s to the point where he can casually talk to her about leaving. The man I love has changed so much in the 4 months he’s known Rebecca, and I don’t know what to do. As for myself, I have tried my hardest to give Thomas what he wants. I’ve said yes every time he asks to leave, I’ve started making dinner more and focusing harder on chores, we have sex at least twice daily when Thomas is here. I am doing everything that I think is possible, but I’m obviously missing something. I’m losing him and I don’t even know why. People of Reddit, has anyone been in a similar position? What did you have to do to fix your relationship? Or was it easier for you to walk away? I love this man with my whole heart, I can’t imagine a life without him. So if I could salvage what I have, that would be my preference, but please be as bluntly honest as possible.