Young couples tend to see marriage as a path to a beautiful future, and it often is for those who survive the rigors of life. They have each other for support, and they can share the good times along with the bad. Starting a family is all part of their future plans, and those days can be a trial. Surviving them together means remembering the vows they took, and that helps them keep their commitment. For other people, commitment to another without marriage can actually be a better solution.
There are many times when the legal entanglements of marriage can be difficult for one or both partners. One person may have a habit of overspending their income on a regular basis. Marriage to this person would mean a loss of assets over time, so being in a long term relationship without entering into wedlock could be a good idea. Other couples with a long history could find they will suffer a loss of income if they choose to take formal vows.