Many legal rights issues and problems arise when people have significant others or life partners and live together without a legal marriage. Traditionally, unmarried domestic partners (whether of opposite sexes or of same sex) have not enjoyed property rights that resemble those available to married persons. Generally, if there is no agreement or legal contract between the parties, you will need a lawyer to protect your rights.
If you’re living with a partner (or planning to live with a partner) to whom you’re not married, you may want to consider signing a cohabitation agreement. This is something that same-sex couples definitely should consider as well.
A cohabitation agreement is a written contract that sets forth your mutual rights and obligations with respect to joint and separate property, as well as stating any other financial or general obligations or expectations you wish to agree upon in advance of (or even after) moving in together.