I (21f) slept with two people after my boyfriend (23m) opened our relationship and now he wants to break up with me.
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Sorry for the long post, I feel as though this is a very nuanced and unusual situation and so I struggled to explain it briefly.
So my boyfriend and I have been together throughout our times at university, coming up on three years now. He is my first relationship and my first body whereas he has slept with a number of people before we got together. We have spoken before about wanting to have a future together and potentially kids once we both have a stable source of income. For the first time in years we are spending a few months apart as he has a graduate job and I don’t. I have been living in my family home and working in hospitality so we haven’t seen each other in a few weeks.
Prior to this our relationship was a little strained due to academic stress and we were arguing for the first time ever. We also almost entirely stopped having sex for months and the relationship felt like it was getting dry. I have a higher sex drive than he does anyway and so it was mostly me who was finding this difficult. We spoke about it and he suggested we opened up our relationship and allowed each other to see other people until we could move back in together when I found a job in the same city as him. He even implied that the idea of a threesome/ watching me have sex with someone else would excite him. As much as this might seem strange to other people I was quite excited he suggested this as I have never really had the opportunity to explore my sexuality. I was experiencing some anxiety about the fact that I have only ever been in a committed relationship and I was worried I would one day regret not exploring more when I was younger. Despite this I still love him a lot and know he is the one I eventually want to settle down with.
Since we opened our relationship about a month ago I have slept with two people, a girl and a boy. I met them both on dating apps, and I was very open about the fact I had a boyfriend and I just wanted to explore. Both people were very accepting of this. I enjoyed the experiences a lot and I ended up spending a few nights with this girl in her apartment. It was mostly just because I find living at home very frustrating after having the freedom of living with my friends/ boyfriend throughout uni and my parents still treat me like a child. She and I only actually had sex a couple of times after drinking and mostly when we would hang out we would just play Minecraft or go to the pub. It was more like a friends with benefits situation. I was very open about the fact I was staying at her place with my boyfriend and she was totally ok with the fact I had a boyfriend.
So anyway, my boyfriend has been planning to visit me this coming weekend and I have been thinking about what he said that he would like to have a threesome. I asked this girl about it and she said she would be down so I brought it up to my boyfriend and his reaction totally shocked me. He went absolutely nuts after finding out I had had sex with this girl already and said he had no idea. He feels like he has been cheated on because I didn’t explicitly tell him that I had sex with this girl, only that I had been staying at her place occasionally. I was sidelined. I assumed that he had also been seeing other people as there have been a few nights where he has not replied to me in the evening or asked to call like he usually does. However he is saying that when he spoke about opening up our relationship he meant only for threesomes and not for us to explore on my own. This surprised me as I got a completely different impression from our initial conversation where we spoke about us both getting a chance to explore before we settled down and became adults. One of my friends from uni also sent me a screenshot of him on a dating app from a couple of weeks ago which I told her I was completely fine with as we were both using them. He says now he only had the app to look for a third, not for him to do his own thing.
Now he is saying that he isn’t sure if he can look past me ‘cheating on him’ and that he needs some time to think about whether or not he wants to be with me. I am completely devastated. I have deleted the apps from my phone and blocked the two people I slept with no explanation. Although I did want to explore I have always been certain that he is the man for me. We get on so well and he is dependable, caring, driven, everything I could ever want in a partner. My friends and family love him and we also share most of the same friends so our lives are intertwined. We have even decided on our kids names and the street we want to live on one day. I have tried to explain to him that this was just a lack of communication and that I never wanted to hurt him. I have never even looked at another person until we agreed to open the relationship. But he is just saying this changes the way he thinks about me entirely. He has barely spoken to me since finding out and pretty much ignored my apologies.
How do I earn his trust back?