Last year, me (M26), and my partner (F28) of 5.5 years decided to open up our relationship. This was upon my suggestion. My partner was initially insecure and anxious, as one would probably expect after hearing a suggestion like this while in a long term monogamous relationship. But she is incredibly supportive and agreed, believing it would help the relationship if I felt that it was something I needed (reasoning was mostly due to meeting at a very young age, being romantically inexperienced, and craving exploration etc).

9 months ago I met someone (F23) who I vibed with really well. Our dates were great, she was sensibly cautious about the enm concept, but clearly very open minded, very understanding, and respectful of my primary relationship. Fast forward and I have fallen in love with her and her with me (so she says). This was upsetting to my primary partner when I told her, but she being the supportive angel that she is, accepts this, knowing it was always a possibility. She hasn't been able to find a connection like the one I have, as the guys that she has liked, have all been very monogamous and they can't get past it. Most nm dudes just seem to want to get in her pants which she doesn't want.

The issue is, I have come to the realisation after this non-monogamous experiment that I am monogamous after all. I too seek strong connection, and casual sex while somewhat exciting in the moment, actually leaves me very unfulfilled and craving emotional intimacy. While I love my primary partner more than anyone else on Earth, I am no longer romantically connected with her. Its not that she isn't attractive, she very much is, but our intimacy (both sexual and general) has heavily declined over time (perhaps the struggles of enm didn't help either). I see her more as family, the closest family I have at that, but I can't get over the fact that we don't seem to be romantically compatible. At the same time, I would like to be free to progress my romantic relationship with my other partner.

On the other hand my primary partner and I share an incredibly strong attachment. There is a level of trust there that I can't compare to anything else, and that same degree of trust does not yet exist with my other partner. I want to maintain the emotional bond that I have, but know that leaving would likely jeopardise that. At the same time I am fearful that if my relationship with my 'secondary' doesn't work out in a monogamous context, I could be left with nothing, so naturally I'm riddled with anxiety atm. I also live with my primary and we are fairly financially entwined which adds another complication.

To summarise, I feel like I can't continue with my primary in a romantic context, but desperately want her to remain in my life and to be a part of hers. I also want to be romantically monogamous with my current secondary, but am uncertain and insecure about our future, and the cost of pursuing it is likely huge. I also don't want to hurt anyone I love, but it seems impossible to avoid.

Any suggestion on how I can work through this would be deeply appreciated. I am not in a great place right now, so I'm hoping other people insights might present some unexplored paths.

Thanks