Reiterating what KMag wrote below: For some, publicly declaring your commitment to one another can have a powerful affect on the relationship. It can communica

Reiterating what KMag wrote below: For some, publicly declaring your commitment to one another can have a powerful affect on the relationship. It can communicate a shared vision and commitment for a lifetime. It is not requisite for that commitment, but it leverages cultural support structures that can help keep a relationship healthy. For me personally, I believe marriage provides a couple with an important concept that they are part of something greater than themselves. This is not an exclusively religious idea (I consider myself an atheist). When times are difficult (and they will be over the course of a lifetime), this bond can help a relationship survive when otherwise the pressure to give up can be significant.