2,036. A Suspicion of Extramarital Relations
Hilchos Issurei Biah 2:12
If a man was suspected of being intimate with one of the prohibited relations, or if a rumor circulated to that effect, then he shouldn’t live on the same street or appear in the same neighborhood as that woman. It once happened that a man was rumored to have been intimate with his mother-in-law and the Sages had him beaten for passing by the door of her home.
Hilchos Issurei Biah 2:13
If a person has extramarital relations with a woman and her daughter, or with a woman and her sister or one of the other cases, it’s as if he was intimate with two unrelated woman. One woman is only considered a prohibited relation because of the other in the case of marriage, not in the case of promiscuous relations. Similarly, if a man’s father, son, brother or father’s brother raped or seduced a woman, she remains permitted to him and he may marry her. This is because the prohibition is the wife of one of these men and there is no marriage in this instance.