Several weeks ago I found iliasm.org (I Live In A Sexless Marriage), an active forum with about 1200 members, 40% women and 60% men, who are not getting enough sex in their marriages. Their definition of "sexless marriage" is one in which there is sex less than 10 times per year.
Only about 5 of the members have reported recovering from the sexless marriage status by increasing the sex frequency to an acceptable level. The usual advice is "get a divorce" or "outsource" (find a Friend With Benefits).
I went through 7 years of NO sex or sleeping together at all, and then recovered (maybe not getting as much sex as I would like, but certainly a lot more than 10 times a year), so it seems my experience is quite unusual and maybe sharing my experience might help others.
I'd also invite others who have recovered from a sexless marriage to share their experience and suggestions.
My history: In the first 20 years or so of our marriage, we had sex about once a week, then there was the 7-year drought, then we got together again and had sex about once every 10 days on average for the last 8 years. Most of the relevant details are in this post: https://www.reuniting.info/comment/95275#comment-95275 (in particular the section that starts "* More communication, don't assume she knows how I feel or how serious the situation is.") which I highly recommend reading. The rest of the thread about "Not Enough Sex" may be interesting too, though it's rather long!
(Note to people not familiar with the Reuniting forum or the practice of karezza: karezza can be defined as intercourse without orgasm. Avoiding orgasm has some benefits that are explained elsewhere on this site. But for the purpose of understanding these "How to recover from a sexless marriage?" and "Not enough sex" threads, you can consider "karezza" to be equivalent to intercourse or sex.)
After I wrote that post 2 years ago, the sex frequency dropped off again. Recently I got unhappy with the once-every-10-days sex, did some more research and took some actions which have increased the sex frequency to a more satisfactory level. I might write about it in a separate post in the future.
I think the conclusions I had in the above post are still valid and apply to both no-sex and low-sex relationships. The only additional thought I have now is this: for whatever reason (probably: financial stability, and wanting to avoid the upheaval and uncertainties of divorce), my wife really seems committed to keeping our marriage together. So, when she understands that I'm unhappy enough about something to seriously consider divorce, she will do what it takes to make me happy - in my case, providing sex at a reasonable frequency.
So, her desire to stay married (and my willingness to divorce if necessary) is a lever I can use to get what I want. If she had wanted to stay married, but wasn't willing to have sex with me, I would have been willing to find and live with a girlfriend, without getting a divorce. That would be another way to resolve the problem.