According to articles that I read on the Internet, common-law marriage is not legal in the state of Washington. Here's the link to one of these articles (entitled "Washington State Common Law Rules"): http://www.ehow.com/info_7822119_washington-state-common-law-rules.html
. In addition, the definition of "fornication" is sexual intercourse between people not married to each other. In view of these two things, I would agree with you that this couple is not married in God's eyes.