Are current marital problems a punishment from God for past sins, and is a wife's recalling of memories of a forbidden premarital relationship and enjoying them considered haram and an act of disobedience?

Marital problems are not necessarily a punishment for past forbidden acts, but sins in general are a cause of calamities. No blessing has ever ceased nor calamity descended except due to a sin. Repentance erases the effect of sin, and one who repents is like one who has no sin. However, a wife recalling forbidden memories and relishing them contradicts the sincerity of repentance, for among the signs of sincere repentance is that the heart does not turn to the sin or remember its sweetness. Therefore, repentance must be renewed, obligatory duties maintained, and disobedience avoided. Cooperation in acts of obedience, increasing remembrance of Allah, and supplication are also advised.