How do I fix this? My view point on sexless marriages is that this is just as serious as having a full blown affair in terms of its insult to the partner wanting sex but not getting it. Marriage is at its heart a sexual relationship.
Both affairs and no sex marriages break that agreement. The main difference between discovering that your partner is having an affair and the sex just being turned off on you is how the injured party reacts. Threats of divorce and other drama.
It all comes to a head very quickly. But most times when a spouse cuts the other off sexually, the other spouse just takes it quietly and suffers, save for the pleading for sex or requests to visit a doctor to see if anything medical is going on. I think that when you are cut off from sex by your spouse, the marriage is in critical condition as one spouse has started actively working against the marriage. You DO need to rule out medical issues first asap. There are only three possible outcomes to the sexless marriage story.
First option is that the ignored spouse just continues on and suffers for the rest of the marriage. This is the default ending that most people live though for a while. The third is that the spouse stays in the marriage, but pursues other relationships for sex. Pleading, begging, asking, telling them how intolerable the intolerable problem is. The trouble is that all these are just words. The louder you squeal about the issue the deeper commitment to option one sticking around and suffering you make to your partner.
This is where you just stop pursuing the dead end of sex with your partner and start preparing yourself to pursue things with other people in general.
Once you have that attitude down, there is a reasonable chance that your partner will have a significant change in their level of interest in you. This is a deeply pragmatic perspective, but there we go.
Unless of course when push comes to shove, when whatever good in the relationship outweighs the bad, the lack of sex and love your partner has for you is ultimately… tolerable, you will stay locked in option one.
If you have nothing to lose, try it.