Hi - new to the site and grateful to find it. 

My boyfriend (53, twice-divorced, three grown kids) and I (44, never married, no children) have a "zig-zag" history: We met in June 2018, were together til February 2019, broke up (nothing dramatic, just "wasn't quite what he needed"), and got back together in January of 2020. In December 2020, I discovered he'd been having sexual encounters with other women - two, consecutively. We went through a lot and did a lot of work to try to rebuild trust. That includes couples therapy, and I had been in individual therapy since our 2019 breakup (for several reasons - self-worth issues at the time, followed by average, run-of-the-mill, global-pandemic-and-mid-40s-female-life stuff, plus healing from his betrayal). In the course of our work, I learned about his interest in BDSM, which does not instinctively interest me, but about which I've tried to open myself up in a healthy way. When we felt we could have the conversation, he showed me the toys he has for BDSM. I have since offered to engage in some activities, which he has declined. He shared during our work that he may want/need to have other partners, but definitely wants me to be his lifelong primary partner. We were in a place of healing from betrayal, and therefore our therapist and I had each made clear that we couldn't consider an open relationship at this point.

About two weeks ago, I discovered he'd been seeking a connection and planning a date with someone new. He had not told me he was feeling this need or seeking this. He shared with me that she is a trans woman, and that he has not had any encounters with anyone in the 13 months we've been working on healing, but it's "hard to get away" from the feeling that he needs a sexual/emotional relationship with a trans woman. I learned that, in the six years after his last marriage and before we met, he'd had two relationships with trans women and two polyamorous relationships. 

I come from a very traditional background, and one of the things I've realized in our conversations is that commitment is very fulfilling to me. For me, commitment is not servile or self-compromising and does not inherently have to be defined as monogomous, but it's pretty hard to break out of that socialization, even as I realize fully that it's not inherent to human nature. I have no problem with the spectrum of sexual identity and, for me, the fact that he is interested in trans women is not relevant with respect to who he is and who any individual trans woman is, though I do have some potentially unfair concerns about sexual health risk. I do, sadly, come from a perspective of scarcity rather than abundance, and am working on shifting that perspective to allow for more openness, joy, and love. 

My boyfriend has been an extraordinary gift in helping me open myself to more of those things just in general. He's a wonderful person whose love and personality have helped me blossom, and our relationship is the best relationship I've ever had - except for the hiding, which is pretty significant because it shatters trust. But because everything else in our relationship is so healthy, I don't want to walk away. I love him, and he loves me. 

Still, I'm pretty overwhelmed right now, and among my many feelings is a lot of fear - for my emotional safety, my sexual health (he's not a fan of condoms and tends to be a risk-taker/thrill-seeker), and my future. I can't figure out where to start. How do I figure out whether there's a chance at this future we both want, heal from another betrayal, consider the future possibility of a one-sided open relationship (I am not personally interested in the idea of seeing other people, though I can see how, in the future, the freedom might be healthy and helpful), set healthy boundaries, hold him accountable, etc.? Would be grateful for your respective experiences if you're a monogamy fan who has a healthy love for a non-monogamy fan and didn't know you'd find yourself in this spot.