No, I'm saying that because marriage is public. Almost every marriage requires a witness (even if it's only the officiant). And marriages are registered with the government. If you don't do it the right way, it's not considered valid by the government, and other people aren't legally required to honor it (and maybe not socially--in the past it would have mattered more than it does in 2014).
That's what marriage is--a contract the -rest- of us are required to honor.
If you don't want other people to be invested in your marriage, you can just have whatever private commitment ceremony you decide, and be as committed as you'd like. Lots of people are firmly committed without ever marrying.
And lots of people have marriages in which they have no emotional commitment. But that marriage is legally binding. (and trying to make it more emotionally binding, or at least respectful, is what's behind the idea that I won't acknowledge and will in fact condemn your breaking of that agreement, that contract before it is completely dissolved.) (edited to add the underlined)
Marriage is a contract that the rest of the society and culture have a stake in and are affected by. The other stuff is emotional woo-woo (however powerful that woo-woo is, which can be "very").