S*x once a year on ace terms

Hello fellow aces!

I'm writing a story about a relationship between someone who is asexual (and demiromantic) and someone who is allosexual. I really want to send the message that sex is not necessary, but I can also adknowledge that it may be unrealistic for an allosexual person with a fairly active libido who finds the asexual person very attractive to just go without any action ever, so I've been trying to think about a compromise that won't invalidate the asexual person, but still give it some believability. Just for info, I decided to leave it up to interpretation why the asexual person does not want to have sex, so it could be any reason really.

Anyways, so far I've only been able to come up with one scenario, but it's one I find very interesting and now I'm just wondering what types of asexual people would agree to it and how far I can push the aversion of the asexual person in the story before it becomes unrealistic or invalidating.

So, now I'm asking you. Would you agree to (theoretically) have sex once a year, under the circumstance that you have complete control, can deny your partner that one time if you so please, even right in the middle of the act if need be, and there is no obligation to perform, enjoy the act or reciprocate any sexual attraction or desire? And if you did deny it, you wouldn't have to think about it until the next year, granted that you do discuss the denial and make sure your partner is not growing resentful or developing depression, whatever it may be.

It would basically be an act of love on the asexual persons end, something to do because they love their partner and not because they actually like it themselves. But would you do it under those circumstances?

The characters overall relationship would be a type of BDSM relationship, which is non-sexual for the (dom) ace person and can be sexual for (sub) allo, but they are not allowed to act on any urges unless the ace person allows it.

This is all under the assumption that the allosexual partner will not demand sex if it is denied that one time a year, cheat on the ace person or contemplate breaking it off without a big fat discussion about it first.

I'm making this post because I value your opinions, so please don't be afraid to be brutally honest.