What is the ruling on one who has intercourse with his wife's daughter without penetration, and does that affect the validity of his marriage to his wife?

The husband and the girl must hasten to repent from sins and seek forgiveness from Allah. They must change their dwelling and avoid mixing with the wife's daughter to prevent the recurrence of the sin. The jurisprudential ruling is serious; direct contact with lust (kissing or touching) transfers the prohibition of affinity (hurmat al-musahara) according to the Hanafī jurists. Thus, the woman's mother and her daughter become forbidden to the man and his sons. Some Hanafīs have issued fatwas for the annulment of an existing marriage due to touching with lust. Although there are other opinions that do not consider the prohibition of affinity to spread except through sexual intercourse in a valid marriage, no sane person would accept the husband remaining exposed to falling into sin. Rather, he must close the doors to temptation and distance himself from its causes.