A common law marriage is not formed within the borders of WA. However, if a common law marriage was formed while a couple lives in another state that allows the formation of common law marriage, then that couple has the same rights and responsibilities like any other couple legally married in WA.
You may want to review your facts and options with an attorney.
Common law marriages are recognized in Washington, but common law marriages are not established in Washington. This is to say that if you already have a common law marriage from another jurisdiction, it will be recognized, but not if your only place of residence is Washington.
That being said, Washington does recognize what are called "meretricious relationships" These relationships deal with the division of property at the time of a break up between two people, gay, straight or otherwise. They have largely been used within the gay community. Examining a meretricious relationship and its existence is best handled by an attorney that deals in that area, and I suggest if you think you are in this situation you consult an attorney.