The subject of this thread caught my attention. I would like to see what would be the answer to this question but it seems that it all comes down to examining what the MLCers tells us. Isn't it true that when we marry that there are things that arises (aside from being cheated on)? I would eventually gain weight, my hairline would start to recede, more gray hair shows up, and due to having kids the romantic vacations turns into Family vacations because of the budget? Maybe to rich families this "excuse" can't be used so it would be something else. Now as far as I remembered when I married my ex-wife 12 years ago my height was 5 foot 5 inches.(so much for being "Tall","dark", and "Handsome"). At BD one of the things that was brought up was my Height, I wasn't tall enough for her. So for me, despite her denial of having a third party involved I knew and felt that she already had someone else. Turns out the OM is 5 foot 11 inches tall.
What I am trying to say regarding the question how come we didn't see it coming... because they loved us for who we were until someone else came into the picture. We also had a list of what we were willing to accept and put up with when we married them but because we love them we accepted it or made some compromise in order to make this relationship going. If it were us that fell into this temptation, then we could be giving our spouse this list of complaints why we are leaving them.