"Umm, I like you enough to stay married and I think we are good parents and partners. However, you just don't float my boat sexually so I will boink you a few times a year when I am totally relaxed, you are totally relaxed and the spirit moves me. Otherwise when under daily stress I will wrap myself in a comfortable bubble where I will mb as necessary and sexually ignore you until the spirit moves again. OK?"
I truly don't think this is about you. I'd rewrite the above to read:
"Umm, I like you enough to stay married and I think we are good parents and partners. However, I'm not willing to think about what floats my boat sexually for reasons I'm too uncomfortable to delve into, so I will boink you a few times a year when I am not too scared, you are not too demanding, and there seems no way to avoid it. This is the way I want us to live and you'll have to do it (or not do it) my way until something changes in me, which I hope you aren't holding your breath for, but which is not totally out of the question. Meanwhile I will wrap myself in a comfortable bubble where I will mb as necessary, quickly and alone, run my life, go to work, play with the kids, and sexually hide from you except on those not-too-often occasions when I can't put you off."