Couples living in a live-in relationship do not have a binding (legal or as married couples) on each other.
Lets take a case where such a couple decides on having a baby, everything goes well and they have a helthy baby. But gradually as the realtionship progresses, the initial excitement starts to wither and responsibilities start to rise - i.e. baby care, additional expenses etc.
The relationship goes from bad to worse and the couple decides to part ways. Since they didn't have a formal commitment, the man decides he does not want to take care of the child.
The woman is all alone with only herself to take care of the child. She moves to a new flat, looks for jobs but can't find any...
I might continue but the only point I want to make it is that for any relation which is built around co-operation between 2 people, it is in the best interst of both to formalize their commitments.
Businesses do that, people in partnership do that. When "marriage" provides you with the mechanism to do that - embrace it. Not only does it remind and re-enforce your commitments, but also creates a much deeper bond.
