I’m a straight-identifying Aussie guy in my mid-20s, and I have recently started living with my girlfriend of just under two years. Let's call her "Mathilda."

I need your help.

I feel I need to start by mentioning that most of my prior "serious relationships" have been marred and ultimately ended from full-on cheating or some degree of infidelity, by either myself or the other person. I discovered you at the Festival of Dangerous Ideas in Sydney a few years ago at what would be the week prior to the conclusion of my previous relationship.

With your help via the introduction to the ways of the "monogamish," and taking some time as a single bloke to work out who I really am and what I need from relationships, I was able to accept within myself and "come clea"’ when I put myself back out there and eventually met Mathilda. Successful monogamy in a LTR isn’t possible for me.

Before Mathilda and I started dating seriously, we discussed at length monogamishamy, "what happens when we fuck up" rather than "if we fuck up," and our shared desire to have sex with other couples. I introduced her to your podcast, and we watched the recording of your presentation at the Opera House on YouTube together. Mathilda had told me she always wanted to explore sex with girls, and banging other couples seemed like a safe and exciting environment for her to explore. It also had the bonus of being a great opportunity for me to occasionally fuck other women, and try my mouth on a cock or two eventually, which is something I recently felt has been calling out to me.

I hated the jealous piece of shit I could become in monogamous relationships, as I always found myself trying to catch out my partner with what I knew to be true: They wanted to fuck other people. Obviously they did—because so did I.

I told Mathilda what I wanted, needed, and could offer in a relationship; that I couldn’t stand how jealous I always ended up becoming in my past relationships; that I believed a degree of mutual openness could prevent that arising in me; and that I wasn’t prepared to make (another) commitment that I couldn’t keep. And to top it off, the thought of her occasionally "getting some strange" and sharing details or photos was pretty damn hot.

Even though Mathilda vowed to never sleep around without me, we shared the same views on the matter of monogamy and swinging, and formed what appeared to be a highly successful, trusting monogamish relationship, one that I thought could go the distance. Mathilda didn’t need sex as often or the same way as I enjoyed, but I’ve always considered myself someone with a high sex drive, and now I had an approved outlet to satisfy those needs elsewhere if the need should arise, so I didn’t mind.

After about 10 months of being "slightly open," Mathilda asked to close our relationship, stating that she could no longer stand the thought of me fucking someone else. Truth be told, sparing a single kiss with a stranger on a dance floor, I had no other explorations of openness to report. We talked about it for weeks, before landing on the “we can still fuck other girls or couples together” compromise.

We eventually found one couple online that we clicked with, and really enjoyed fucking, and we tried to see them semiregularly for dinner, drinks, and sex. It was fantastic. We all got what we needed, and it worked particularly well for me, as I got to explore some light BDSM and other kinks with the girl of the other couple, which wasn’t an opportunity that I got to explore within my relationship. I really loved how close and intimate things with Mathilda and I would be in the moments and days after allowing each other to sleep with the other couple.

The couple moved at the start of this year and naturally my interest in reactivating our online profile and searching for new local replacements sparked a couple of months later. After putting off talking about finding another couple, Mathilda tells me that she does not want to sleep with other people "for a while." After talking about it in depth, she confesses that although she is glad we fucked the other couple, she doesn’t want to do it again any time soon, and only said she wanted to do it the subsequent times in order to please me. She didn’t like the idea of the occasional outsourcing of a pro to fuck me either, but told me I could explore with as many men on my own as I wanted, as that “wasn't something you could get from me.”

I did the right thing by telling her what I want, need, and could offer before our relationship started, right? I feel like she told me what I wanted to hear and bit her tongue until we were in too deep. Now I’m sharing a house with her and supporting her through law school, and she’s changing the rules of the relationship and pleading mercy. I’m going out of my fucking mind.

We have average, vanilla, weekly-ish sex, but I no longer get the opportunity for hot, sweaty, athletic and subby/dommy sex that I crave on those rare occasions. And this all ended before we took the opportunity to find a couple with a bi-curious/bisexual guy with whom I could explore. Also, she’s put on about a fifth of her body weight since we met, and I’m finding myself less attracted to her as the months go on—which is somewhat of a blessing in disguise considering our mismatched sex drives, because I am now less likely to ask her for sex when she’s not feeling it. She’s unhappy with her weight but not unhappy enough to make any changes. I’m a personal trainer, I work with dozens of driven, sexy, and flirty female (and male!) clients and colleagues every week. But I'm spending all my free time masturbating furiously to thoughts of other people and resenting my partner.

It seems like the obvious thing to do is to leave her. I know we’re both young, and there is probably a better match for me out there, but the non-sex part of our life together is brilliant. She is my best friend and an extremely loving and caring person. We make a wonderful home together. She has supported me and helped contribute to the success of my career. She is the woman with whom I want to start a family. And the thought of fucking up her pathway to becoming a lawyer, throwing all the wonderful companionship away, dividing our assets, sharing our rescue dog, and the rest, all because she doesn’t want to share me with others—it's just unconscionable to me.

Summing up: I can’t accept full monogamy as the price I have to pay for this relationship, but leaving her is not something I can do.

We have talked and fought endlessly about this over the last couple of months and I have no idea where to go from here. I think it is shitty of her to change the rules and not want to compromise. But I can’t help the way I feel about her.

Please tell me there’s another way we can both win.

Boy About2 Destroy A Caring Relationship Over Nonnegotiable Yielding Manwhoredness

Sorry, BADACRONYM, but I don't see a "both win" solution/compromise/scenario here.

It could be that stress and overwork and insecurity are behind her request to close the relationship, BADACRONYM, and maybe she'll agree to open the relationship back up once she's done with law school and after she's lost the weight and/or started to feel better about her body. But my hunch is that she's discovered, after making a good-faith effort, that nonmonogamy just isn't for her—at least when it comes to sharing you with other women. So staying with her means either you're gonna be in a monogamous relationship* (which will make you miserable) or she's going to be in a nonmonogamous relationship (which will make her miserable). And guess what? You'll both wind up miserable in the end if you stay together. Eventually the frustration of the miserable person who caved on the monogamy/nonmonogamy issue will curdle into toxic resentment and consciously or subconsciously that person, i.e., the person who was miserable first, will set out to make the other person miserable too.

So, yeah, no. Just as there's no compromise win/win position when one person in a relationship wants to have kids and the other person doesn't, there's no compromise win/win position when one person wants monogamy and the other doesn't. You're either parents or not, you're either monogamous or not.

And you're a monogamous not, BADACRONYM. You were clear about that from the start—you were clear about who you are, what you need, and the kind of commitment you're capable of keeping. Mathilda is now asking you to make precisely the kind of commitment you know you can't keep and you've told her you can't keep, BADACRONYM, and you would be foolish to make that kind of commitment and she would be foolish to believe you if were foolish enough to make it.

Let's pause here to play let's pretend for a quick second: If Mathilda had told you back when you first got together that she wanted a monogamous commitment and you agreed to be monogamous and then you unilaterally informed her—after moving in together, after adopting a rescue dog together—that you not only wanted to open the relationship up but that you insisted on opening it up right now, BADACRONYM, no one would hesitate to identify you as the bad guy.

So should you end it? No, BADACRONYM, you shouldn't. Mathilda helped you get started and now she's in school and she needs your support. But you should, for your own sanity, and to avoid "cheating" on Mathilda, remind her that you never made a monogamous commitment to her and inform her that you will not have a monogamous commitment imposed on you by ultimatum. If she ends this relationship as a result—if she leaves the nonmonogamous relationship she entered into with you—then leaving was her decision, BADACRONYM, not yours.

* I predict that her offer to let you suck all the dick you want will be rescinded the first time you suck a dick.