Ok.. I do not really think it is just this unmet needs stuff... I would phrase it as unrealistic expectations and poor communication. First let us take the premise that there is no perfect marriage nor is there any one thing that any of us did or did not do that lead to our situations... it is a series of bad choices and decision by both that have lead us here.
In my case, I married someone who came from divorce and who has two siblings who divorced and married their affair partners... so he does not think divorce is bad.. he thinks it is a valid choice that can lead to second chances! Now when I married him.. he would have told you (with sincerity) that he thought divorce was a bad thing and he was marrying for life... and he meant it.... but subconsciously he, because of his life experiences, felt divorce was an option.
Next, many who are in the throes of an affair.. are looking at things thru rose colered glasses... how you can compare the conversations you have with your 10 year spouse to your new girl friend.. can't don't you remember in the early years of your relationship how you talk about everything and nother for hours? Now conversations fall into ruts.. but so what...? The problem when you are in an affair thoguh is that you compare your new relationship to the old.. as it is now.. old, comfortable maybe.. maybe stagnant.. maybe boring.. stuck in a rut, to the thrill of the new! Doesn't that new TV tempt you in the store? We are very much a me generation who wants it all now and who has an attitude of entitlement... we DESERVe happiness... you see it in the work force.. it used to be that you went to work for one company for life if you could.. now everyone jumps jobs to get raises... or because they are bored or because they think somehow they will be happier at a new job.. maybe less office politics or a nicer boss... whatever the reason... now people think spouses are interchangeable as well... Lets go in for an upgrade! The problem is for these saps the remarry without having really looked at themselves (i.e the WAS...) is that a really high percent of 2nd marriages fail. Why.. well it is not until you are living with that person that you realize... hey, its been a few years.. and the sex got boring.. hey just like in my first marriage... that she got boring... perhaps some of those traits you thought were great end up annoying you...then you add the stress of step families and blended families.. and if alimony or child support is being paid.. the financial burden.. the new wife is jealous of the time and attention you spend with your children.. or even with your ex-wife if you need to talk to her al ot about the kids... the stresses on second marriages are legion... but they are there and they destroy a lot of second marriages... so maybe we should all sit back and let our respective spouses just destroy themselves?