Marriage is a huge commitment. I'm on the fence about marriage personally, I don't mind that other people get married of course, but sometimes I think marriage just isn't for me. You're right it is easier to break up with someone if you aren't married to them, on the other hand, that's exactly why some people get married - in theory it holds more commitment and it's harder to end so people tend to work on their relationship harder as opposed to "See ya!".
But still, there are tons of married people that divorce and say "See ya!" too.
If you are going to get married ever, my advice is to date that person for at least 1 year and have a long engagement. There's absolutely no reason to rush marriage, especially if you think you're going to stay together forever anyway.
I know far too many people who got married after knowing the person for only a few weeks or a few months. This is a bad idea. Sure you might get lucky and it could work out, but all the people I've known personally who have gotten married very fast end up divorcing very fast too.
A few weeks or months just isn't enough time to make such a huge commitment to someone. You have to remember you're not only going to live with that person, but you're going to mix all your finances with that person, you also take on any debt they might have, etc...