The courts may recognize certain rights in relationships other than marriage. Palimony is the term for legal property and support rights arising from co-habitation. Co-habitation is not necessarily required for a palimony claim so long as there is a marital-like relationship. The default rule is that title controls ownership in the absence of a written document stating otherwise. However, the courts may recognize certain equitable doctrines to achieve fairness even if strict adherence to the written document would produce a different result. One cause of action is a constructive trust through the theory of unjust enrichment. The crux of the theory is that it would be unfair to allow the person that doesn’t have title to be excluded from the wealth they helped create.
Another equitable doctrine is quantum meruit. This doctrine posits that each party should get what they deserve. To be successful, the parties must establish that there was a reasonable expectation of receiving a benefit from the relationship. For example, a promise to support, expressed or implied, could be the subject of a quantum meruit claim. As a matter of policy, certain courts are reluctant to award any rights in non-marital relationships with the belief that it undermines the institution of marriage.