Gender fluid with a well-meaning but bumbling parter

May be somewhat explicit.

I'm gender fluid and female sexed. I'm in a relationship with a heterosexual, cisgender man who's trying to help in the bedroom, but making things awkward and uncomfortable by doing so.

Throughout my life I've often been unable to enjoy sex when I feel like a man because my body isn't the way it "should be", and have opted out or dispassionately gone through with it. When my boyfriend asked how my gender identity might affect us in the bedroom after the topic came up, I suggested we (meaning him, mostly) simply avoid my genitals and go with anal sex. While it's not a man's body or a man's genitals, it uses the body I do have in a way that isn't obviously not those things and would avoid a lot of discomfort. Both men and women can have anal sex.

I've always enjoyed anal sex and have been comfortable with it. He loves it more than anything in the world and has a million fantasies revolving around it. It was the perfect solution.

Instead of having sex on the one weekend we're going to have together for a long time, we had an increasingly heated conversation on the topic of strap-ons, with me stating that I didn't want to use one to emulate what I don't have and what won't feel like being a man while he rambled on about all the ways it could simulate it. According to him, a strap-on wouldn't replace his penis, but would be better than nothing if he was going to be intimate with someone. I ended it by telling him it wasn't about things like thrusting motions or clothing and went to go do my own thing for the rest of the night.

I feel kind of degraded by this, and I don't think he can understand why and is probably going to continue to try to fix things like this. I don't want to modify my body and pretend I'm not dissatisfied and disconnected while I ram something that doesn't even have nerve endings into his ass. It would be one thing if it was done solely to enjoy giving him pleasure or as part of a roleplay scenario, but not to stimulate what obviously isn't part of my body and isn't ever going to be because then I'll just need a pretend vagina (and with someone like this, it's not going to be so simple as anal sex).

Where do I even begin with this?