As I've said in a previous post - when you're married in the United States, you get a huge tax advantage in addition to not having to pay singles' supplements when traveling.
It's been calculated that remaining unmarried incurs a massive financial penalty over the course of one's life (again, I'm speaking as a U.S. citizen; I can't speak for other countries' laws or provisions).
What financial advantages do I enjoy being unmarried? If I want to travel, how do I keep it from being prohibitively expensive? (married couples can afford to travel anywhere given that they don't have to pay extra per person)
Being un-married sucks in a lot of ways. Being married is far superior.