Read another response by Charles Taliaferro
Is kissing a person on the lips other than one's spouse cheating? What about not on the lips? Does location really matter when it comes to kissing? I don't think it does, and even when it comes to major slip ups as much as penetrative sex, I don't think that's cheating either because promises are but a CONDITIONED vow of not doing any of those things. Because promises between a couple are usually not very precise unless lawyers are involved, I think the greater subject of importance is whether the other person FEELS betrayed and whether there are romantic feelings beyond sexual ones. A condition/promise, I think, even in marriage, is, "I love you so long as you fulfill and do such and such...conditions according to MY needs of such and such." So in other words, because you slept with another person, that does not mean you do not love me, but it does mean you do not love me "to the best of your ability" and so "I would like to change that fact." Do philosophers care for human feelings?