Loyalty wavering

I have been in a DB for a while and have tried to work with my wife to solve it, but to no avail. Back in the beginning of the year I told her I wasn't pleased with where we were and I wanted to work together to do more. It worked for about 2 weeks, but come March and since it has completely dropped off to zero. I am tired of trying, this has been going on for 3+ years now. But loyalty is important to me, especially with the vows we took and with sticking it out through the good and the bad. But after 26 years and no end in sight, I am wavering and I have urges, the bad is bumming me out. So my question, do you think people in long-term sexless marriages owe each other monogamy if intimacy is completely off the table? I am struggling with this, I will admit. Thanks