2,212. One Doubt for a Kohein, Two for a Yisroel

Hilchos Issurei Biah 18:9

While the wife of a kohein who tells her husband that she was raped remains permitted to her husband, she is rendered prohibited to any other kohein after her husband dies. This is because she established herself as a zonah and rendered herself prohibited.

Hilchos Issurei Biah 18:10

When a kohein betroths a woman, whether she’s a minor or an adult, if he engages in intimacy with her and then claims that she had been with another man, she is rendered prohibited to him out of doubt, i.e., whether it happened before or after he betrothed her. When a Yisroel makes such a claim, however, there is a double doubt, i.e., whether it happened before or after betrothal, and whether she participated willingly or under duress. This is because a woman who was coerced is permitted to remain married to a Yisroel, as we explained in halacha 18:7.