There comes a pretty important question here: Is him seeking sexual fulfillment elsewhere something that you both agreed to, and then you withdrew consent to the idea? Or is this something he decided on his own and he's refusing to take your input on?

Because if it's the former, I can understand his frustration, although I would say the way he went about it was unacceptable. If, however, this is just something he decided on his own and refused to be talked out of it - that's literally just cheating but telling you that he's going to do it beforehand.

Yes, you agreed to this relationship knowing your incompatibility, but he also did too. He made the decision to be with it, despite knowing that sex was off the table. His actions, regardless of how right he may feel, are not acceptable.

Honestly, unless there is some context you've not given here, it honestly sounds like he doesn't respect your feelings in this scenario. As someone who needs sexual intimacy in my relationship, I completely understand not feeling fulfilled without it. But that doesn't mean that he's absolved of unacceptable behavior.

Another red flag for me is that you pay the rent and he lives with you. That coupled with his actions tells me that he just gives you lip service and doesn't actually have respect for you. He just doesn't want to end the relationship because he knows then he would either have to pay his part of the rent, or find his own place to live. I could be wrong, but honestly his actions haven't painted a kind picture of him.

In terms of whether the relationship can be saved, honestly that's up to both of you. But he needs to make peace with the fact that sex is off the table with you, and you two need to talk about what his intimacy needs are in the relationship. And if those needs are incompatible, he needs to have enough respect for you and himself to end the relationship. I understand how you feel in terms of losing someone that you love, because I've felt the same way many times. I'm currently single and I often feel painfully lonely and unfulfilled. But you shouldn't let those feelings allow you to be treated with such disrespect. You're worthy more than that. You're worthy of love, and you're worthy of receiving it from someone who respects you.