How do you feel about marriage, sometimes I feel like it's necessary but others times I'm not so sure
Well, marriage is just a socially or ritually recognized union between two people, so if you don't care about either of those, than it doesn't matter.
So does it date back to the  bible or something, or is it just something people do because others do it
I'm not too sure about that, but different religions have different definitions of marriages. Are you married?