What does marriage mean, or how bad would it have to be to get divorced?

For most of my (short) grown-up life, I have been of the opinion that marriage should be forever, and once you make that commitment, you better honor it. My father left my mother when I was young, and it was a terrible situation for my mother and for us kids. So, ever since, I have thought that once you get married, you should be in it no matter what.

Recently, I have come to know someone who was in this situation: the marriage wasn’t horrible, but over time, they came to realize that they would both be happier without it. There wasn’t any abuse, or even constant fighting. Both partners grew to want different things, and they mutually agreed they would be happier outside the marriage than in it.

This contradicts the no-matter-what view of marriage, but I think they made the right decision. And it made me reconsider what marriage really means—if it really is wise to commit to something no matter what, when that specifically means that we might be sacrificing our own happiness.

I guess these are kind of a lot of barely connected thoughts, but I would be interested to hear what you older and wiser folks have to say on the matter.