First, I want to say that I’m very much not trying to pressure someone into doing something they don’t want to. I know that is no way to set ourselves up for long-term success. That’s a fast track to creating a lot of resentful feelings that will rot a relationship. What I’m looking for is more of how to shift someone’s mindset to be more open to possibilities of something more than strict monogamy. I’m struggling to come up with any perks that for him that would make him desire something more than we have currently.

I (36f) have been happily married to my high school sweetheart (36m) for 8 years. We have a wonderful life together. A very stable relationship full of love, laughter, passion, and care. All of our needs are met and we are happy.

Where this gets complicated. What started as a joke and what I thought was an easy side gig selling feet pics morphed into me having some online submissives. Husband has been very aware of all of this and I have a lot of boundaries that I always stayed within (big ones are that I don’t share nudity and my pleasure stays out of it). This has been going fine and I’ve become friends with some of my long term subs, which is not an issue. But somehow feelings crept in with one of them (37m).

So at some point I had a random fantasy of a throuple. Not just a threesome, a fully committed relationship. I started talking to this guy about it and just asking hypothetical questions of how it would work. Topics ranged from spicy to completely mundane. Who does the dishes? Who gets shotgun in the car? What are the sleeping arrangements? How conflict be handled? He was extremely interested in the idea as well. As we talked I started to see how extremely compatible we are and what went from a random fantasy with no one in particular as the third quickly evolved to planning a hypothetical life together for the three of us.

I shared this fantasy with my husband as well and he was mortified. He struggles with a lot of insecurities and has always worried that he isn’t good enough for me or doesn’t deserve me (I feel quite the opposite about that and he knows it). So this felt like me saying that I needed something that I’m not getting from him or that I would rather be with this guy than him. Not at all how I feel. We’ve had a lot of discussion about this and I think I have him understanding my perspective now, but I know those negative thoughts creep in still.

But still, my husband remains the most patient and trusting person I know. This guy and I continue to talk about the throuple and our feelings for each other are growing stronger. He even flew out to visit us for a long weekend. We had a lot of boundaries around it and it was a purely friendly visit, but everyone was respectful and we all had a great time together. I truly could see these two having a heterosexual bromance together (both are straight).

So where we are at is that this guy and I are craving so much more (emotionally, physical, commitment, all of it), but husband remains uninterested. And the problem is that I cannot blame my husband for not wanting to risk ruining what we have for something that he sees little incentive in. I see perks for me. And I see perks for the other guy (currently single). But nothing that I’ve said to my husband is appealing to him. And he is so very stuck on monogamy being the only way. And concerned about the judgement of others.

This would be completely uncharted territory for all of us and we would take it very slow. It would be long distance in the beginning, but ideally we would be working towards him moving in with us.

Is this a lost cause or has anyone had success shifting their partner’s mindset to be more open?

TLDR: I’m happily married, but crushing hard on another guy who I think is perfect throuple material (and he agrees), but husband is not open to more. Looking for advice to help him be more open to exploring slowly.

Edit to add: Thank you all for your feedback. A lot of what you have said are things that I already knew, but didn’t want to face. Sometimes you just need to hear someone else say it. I will be slowing things down with the other guy and focusing on strengthening my relationship with my husband. He comes first. Always.

However, I think what I was trying to get at was understanding how existing couples move from a place of monogamy to ENM. Like there is no way both partners wake up one morning and both all in. Realistically, the thought comes to one partner and when they tell the other there are a wide variety of reactions they could have. I would assume many of them start from with a negative first impression (due to social norms and self conscious concerns, amongst other things), but I’m sure that some of those people (not all) warm up to the idea over time. I want to know what drives someone to move from that initial negative reaction to a more positive, open perspective.