I know I shouldn't type this (btw, this won't be as exciting as those opening words might suggest), but I am in a very unconventional relationship. Not married, but been together over 14 years. She had a brain injury 13 years ago, and I'm now mostly a caregiver. I don't mind helping her with stuff. She's awesome most of the time. Not the same as the woman I fell madly in love with, which is a pain I'll never get over, but awesome most of the time. In addition to the numerous, though relatively mild, disabilities, she has fits of rage. They are regular, and often intense and long-lasting. Screaming, breaking everything in sight. It's hard to explain, but it's very difficult to keep from hurting herself or you. Her family all lives close by, yet they don't come around much partially because of the fits of rage. These are good, caring people. I get annoyed with that a little from time to time, but I get it. Plus they have their own busy lives.
It sucks sometimes, but we manage. I lead a pretty happy life. Not what I expected, but I feel it's the right thing. She's great most of the time, but not in a conventional wife way. It's not like having a true partner. The fits of rage aren't fun, but the loneliness is the hardest part. Living with someone that you really can't discuss important things in life is difficult (hard to explain, but that's from a combination of central auditory processing issues, speech disorders, an inability to follow complex stories, and frankly, a self-centered focus, which is understandable in her situation).
I have to find other outlets for what I'd consider typical adult conversation. My family lives far away, which sucks, but my work is here and I work 70 hours a week. My main outlet is friends, and obviously work because that's where I'm always at. I have some good friends, though I don't have the ability or time for a lot of things. Frankly, this board helps too.
The point is I'm probably a prime candidate for an affair. I'm pretty sure I could have one and no one would blame me, even her family. Once people get to know the situation a little, they are surprised that it hasn't happened.
It, of course, has crossed my mind though. Luckily, I've never had a terribly high libido, but it has crossed my mind. There are number of reasons it hasn't happened, but one is that I don't like drama. I run a business, and don't need that crap. Maybe, by some miracle, I could "get away with it" on my end, but the person on the other side would likely have attachments on their end.
I don't think it'll ever happen, but I'd never say never. And I have thought that if the urge to step out ever overtook me, then a prostitute would make the most sense. Never been to one, but it seems much less messy (in the figurative sense).