It's the idea that if you love your husband or wife but you still are attracted to other people, there's something wrong with you, there's something wrong with your marriage, something wrong with your partner.
É a ideia de que, se amarmos  o marido ou a esposa, e nos sentirmos atraídos  por outras pessoas, há qualquer coisa de errado connosco, com o casamento ou com o nosso parceiro.