I'm female but I don't see that it matters in the situation described. If I worked away from home for years to support my family and found out that my partner had been having an affair, I would feel totally betrayed and very used.

I'd have to walk away from that relationship immediately but I have self respect and am strong enough to do so, many others aren't.
If you are not happy in a relationship why cheat? We all have choices (many find excuses not do the decent thing) and we are responsible for our own actions and behaviours.