Does WA state recognize common law marriage, WA cohabitation, meretricious relationship

No....... That being said, the courts have been developing a body of law revolving around Meretricious Relationships. If a couple acts like a couple they might be considered in a relationship that should be divided in the same manner as a marital couple. Without more information it is hard to answer the question more fully. I have done a short piece on this subject. I have added the link below.