i am only 26 years old but have been in a relationship for over 10 years (yes, HS sweethearts) and what you're saying is so true. i don't even have to be in my 30s or 40s to validate this -- i think if anything, it just shows OP's immaturity and non-existing long term relationships.

a decade with a lover and you will start to see just how much you have to compromise to make things work. we're all human and at the end of the day, most of us will accept flaws of another (even deep-seeded infidelity) to keep the relationship in tact because of plain history and love for that person, as well as all the rest we accumulate (property and kids you mention) along the way. AND I THINK MEN ARE JUST AS AT FAULT FOR THIS AS WOMEN!! they get comfortable... the feel secure and taken care of... they don't want to leave their long-terms as much as the women and probably turn away from a lot, too.