Masechet Kiddushin Perek 3 Mishnah 11

A man says to a woman, “I got engaged to your daughter.” She says, “No, you didn't get engaged to my daughter. Rather, you got engaged to me.” So over there, the same halacha (Jewish law) applies. A person now has prohibited certain items onto himself. So the man who's claiming he's married to the daughter is now forbidden to marry the relatives of the daughter, of the younger girl. According to him, they're his wife's relatives, so he can't marry those relatives. But the young girl who he's claiming to be married to is allowed to marry his relatives, because his claim is not bound. She's not bound by his claim. She never claimed to be married. So therefore, she's allowed to marry his relatives. He's allowed to marry the relatives of the mother of the older woman because he didn't say that he was engaged to her. But the older woman here is forbidden to marry his relatives because she's claiming that she was engaged to him.