For example: a man owns his own home and a woman owns her own home. They are friends and spend time together living alternately in the man's home and then the woman's home. (They usually switch homes every 3 to 5 days.)
"Cohabitation" means "living together." Based on your statement of facts, you are cohabiting. However, although South Carolina does recognize common law marriages, you may or may not actually be in a common law marriage. There are many factors to consider. Get an attorney's opinion, if this concerns you.
Not sure what your question is, but cohabitation literally means the act of living together. Statutorily it may include the act of living publicly as husband and wife, known as common law marriage. Not many states recognize this type of marriage anymore. In the few states that do, the parties would have the same legal rights and responsibilities as legally married couples.