This happened to me in my 20s. My ex refused to touch me at all in the last year we were together and it completely wrecked my self confidence. I've always had a high sex drive and consider sex to be a display of love and a way to bond. So having a man refuse to go near me was soul destroying. I did everything I could to be the perfect girlfriend and it had no effect. And I'd never heard any women discuss this situation (usually it's the opposite way around) so couldn't talk to anyone.
He eventually admitted he was gay and had been chatting/flirting with men online for years. Logically, I know he can't help the way he is wired and I shouldn't take it personally. But living like that for so long has destroyed my self image.
My sex drive is ridiculous now, as I feel like I need to prove men still like me. But at the same time there are far less available men in my dating pool who want a relationship and I'm not interested in one night stands or married men. So I feel as though I'll be alone forever now. If I liked younger men, then I'd become a cougar as there are far more single guys under 35, but I don't.
I am sympathetic to anyone stuck in a dead marriage (especially those with kids who feel trapped). It is a horrible experience that can have a huge and ongoing impact on your life.