You guys always seem to make light of those little affairs.
They are devastating to a marriage, it may just be sex on the side to you but to the woman it is the end of the relationship and trust. It may take a few years for it to dissolve the marriage but eventually it will and the woman will find she doesn't love the man anymore.
You only see the 'doesn't love him anymore' and not the actions of the man that brought her to that place.
You should look to the possible immorality of the men in their relationships and not try to simplify the failure of the marriage by always blaming the woman.
I see you defend your father for his affair yet condemn your mother for not being able to manage finances. You got some issues in there dude.
re: Affairs, Divorce, & Dividing Property
The trick here is that there is a natural inclination to give favor to a cuckolded spouse. A spouse doesn't deserve a financial award just because they were cheated on. That gives them too much credit, and may ignore the fact that they were a poor spouse, for example. A cheating spouse doesn't deserve to be financially punished, either.
Adultery is a lot more complex than a lot of folks are willing to consider. It's a reason to leave a marriage. It's not a reason to clean-out the cheater, or unduly benefit a person who just had the fortune to be cheated on.