It's not all about the media or having unrealistic expectations. I truly believe the more "options" one has the less crap they accept.
During the 1950s and earlier it was common to have one income families. Usually it was the man who worked outside of the home. A lot of households also had only one car. In many ways a wife was totally dependent on husband. Limited forms of birth control methods also probably kept some people in line with regard to having several sex partners or cheating. In past eras there were lots of folks who were either virgins when they got married or had only had one or two sexual partners. Many couples stayed together not because they were "happily married" but because they actually "needed" each other. Couples were forced to share a car, television viewing, and household phone.
Fast forward to today where women are in the work force in major numbers and gradually earning more and more money. The birth control methods have improved so much that they can now have sex on par with a man without worrying about getting pregnant. Men celebrate this as well because it means more women are willing to have pre-marital sex.. Everyone has their own car, cell phone, and each house has multiple televisions. There is very little need to share anything. Options and more options.... Once a couple marries and find themselves going through a "rough patch" they have less of need to compromise.
Personally I think this is a good thing. At least today the odds are in your favor that if you spouse is with you it's not because she or he "needs" to be with you but rather it's because they (want) to be with you.
The media may be a contributing factor with it's Hollywood endings. However we have always had fairytales and romance novels. The biggest change has been women in particular having more options! It's been stated that in the U.S. 66% or 2/3rds of all divorces are initially filed by women. They don't have to put up with the same crap their mothers and grandmothers did.