What is the ruling when a non-wife (foreign woman) claims defamation, and the man claims she was his wife at that time, but she denies the marriage?

Primary text

If a non-wife claims a man defamed her, and the man asserts that she was his wife at the time of the alleged defamation, the statement of the woman denying the marriage is accepted. This is because the default legal premise is the absence of marriage (*adam al-zawjiyyah*).