It isn't the license that matters. It is the mutual contract entered into by the contracting parties. In Oregon marriage licenses are not a prerequisite to having a valid marriage. Frankly, why should anyone have authority to grant permission to marry? Oregon recognizes that marriage is an agreement between the parties thereto that no outside entity has any authority over, and, although you can get a marriage license, you do not need one to have a marriage recognized by the State of Oregon.

When people vow to one another sexual monogamy, that is a contractual obligation, whether it is called a marriage or not. Violating agreements is at issue here, not whether the state or the church authorizes such an agreement.