I think a "natural outcome" of events is that the starved partner would eventually want to get out of an R that is unfulfilling to them but cheating is a selfish choice to make and, really, what are you saying if you cheat? "I am so special that I deserve to have both a spouse and a girlfriend/boyfriend"?
I can testify firsthand to how strong the temptation can get when your needs are not being met at home, but it is still not the logical 'next step', imo.
