I would say, from what I've seen, that it's a mixture of everything said above. First, men and women are often not top by the Church or by their parents what their roles should be in a marriage. Also, both at times, want to be in control of everything, and not realize that only one can be the leader. (There is a reason the game is called follow the leader, no leaders.) Then we have a society that pulls on us, telling us that we need to be more this or more that, or else we can not be a complete person; that if we don't live our lives a certain way, meet certain standards, than we are a complete failure. Finally, we live in a society that is all about the here and now. Many students do not have to suffer consequences in school, and give up. Given this mode of method, when challenged in a marriage, it's easy to say, I give up. Marriage has become a fast food commodity. One other thing you didn't mention is that sometimes families are literally trying to tear couples apart. I know of one, where the family hates their daughter-n-law, and have encouraged the man to divorce her. From the start, they have chosen to hate her, and not try to know her, where she has made several advances to bridge the gap between them.
The only way out of this is to have people humble themselves before God and seek His face. Churches and families need to rise up and mentor new couples, as well as support them through prayer and encouragement. When someone comes to them seeking advice, instead of saying right away, "Oh, your so right, you poor thing", they should help them look at it from a different perspective, the spouses. People need to realize that a marriage is a life long covenant with God, not a commitment that can be broken at the first sign that someone hurts you (If they are abusing you, however that is a different story. I think you need to find help as fast as possible, in this situation.) As Christians, we need to realize that we can not run away from every problem. Sooner or later they will catch up to you.
