There are many reasons cohabitating couples may cite for not getting married. Some may say that they do not need a "piece of paper" to prove their love and commitment to each other. Other couples choose to live together without getting married in order to avoid the legal entanglements that can arise should the relationship end. Couples basing their decision on the latter reason should bear in mind that although cohabitating relationships often dissolve fairly simply, that is not always the case.

Perhaps the most notorious example of the legal quagmire that can surround the end of a cohabitating partnership is the case of Lee and Michelle Triola Marvin. Lee Marvin, the famous actor, and his partner, Michelle, lived together for several years before deciding to call it quits. When they did, Michelle claimed that she was entitled to support and an equal division of the property acquired during the relationship, but the actor disagreed.

Michelle claimed that she and Lee had an oral agreement that provided that while they lived together, they would "combine their efforts and earnings and would share equally any and all property accumulated as a result of their efforts whether individual or combined." According to Michelle, the agreement also provided that Michelle's contributions would be in the form of her services "as a companion, homemaker, housekeeper and cook." Michelle sought the help of the California courts in enforcing this alleged oral agreement, such that she would be entitled to half of all of the property the couple had acquired.

The first court to hear the matter held in favor of Lee Marvin. Michelle appealed, however, and the appellate court agreed with her, at least in theory. It concluded that adults who live together are just as competent as any other individuals to enter into contracts regarding their earnings and property. The fact that a contract is not in writing does not necessarily make it unenforceable. Even implied contracts, the court stated, are worthy of enforcement.