It was? That could be true, but really - there are so many marriage customs going back so far in time, it's impossible to know for sure if any religion can really claim ownership over it. Different cultures and religions have different marriage customs, but of course we didn't do our marriage according to
them anyways.
I think marriage, the solidifying of union between two lovers, is popular for a reason and I think it has little to do with religion, actually. I believe it is competitive as a meme (
meme theory) and as a strategy because of various reasons. Like it facilitates cooperation in raising children, it caters to people's possessive feelings (you don't want to share your partner) and it helps keep cooperative couples and families together.
These are just a few points and I'm obviously just scratching a surface, but I imagine that if a society didn't have marriage, that society would probably become more competitive once marriage did evolve in culture and became popular. More incentive for people to cooperate about raising kids and building value to their lives would have a multitude of consequences.
As for personal feelings about it, I didn't feel a loss of freedom when we married. Being a husband is pretty much like being a boyfriend I'd say. We have two incomes instead of one, so that gives us way more economic freedom. We both "dare" to invest in things like a house partly because the other can't just run away from it all. Unless you'd rather be with someone else than your wife/husband, the real "loss" of freedom comes with children.