That doesn't really seem like the best solution, that will just totally destroy the whole relationship. And suicide is just the demon creeping in, don't pay attention to that. It's not a solution....

I think you have something missing in your relationship. Witout that third leg it's more like you're just friends. Is your partner also depressed or on meds that might kill libido? There's a piece to the puzzle that got lost under the couch or something on their end, it seems. And talking it over together alone hasn't seemed to work. Have you gone together to a relationship T? Or perhaps something phsyical is going on like an underlying illness?

If you've hit all the bases and you're this unhappy, then it probably is better to move on so you can both find someone right for you. Because I know if my husband was that unhappy and constantly going out to find someone else, even for "just that," I would be crushed and that would end the relationship and destroy all the positive aspects that had ever been as well.