Marriage is quite simply a bad idea.
Even though scientific studies indicate married people are, on average, happier than single people?
I wont argue against that, but are married people happier on average than two people who are together but not married? I doubt it.
I looked it up, and at least one study says it's equal in the case of cohabitation, which is pretty darn close to marriage when it comes down to it. People who are actively dating are happier than single people, but not as much as married or cohabiting people.