What is the ruling on the son marrying in the apartment that his father bought for him, knowing that the father still deals with usury? Does this affect the ruling on the rest of the family members living in the father's apartment? What is the correct legal course of action in this situation?

Before answering your question, we must alert you that withholding zakat and consuming usurious gains are two grave matters. You must strive to deter your father from them by all lawful means, especially since your father loves you.

Regarding your question, you mentioned that your father's wealth is not entirely consumed by usury and zakat. This means that accepting a gift from him is permissible. Therefore, accept the apartment your parents intended for you to live in and marry in. As for the possibility of your father repenting, rulings cannot be based on it, as it is an unseen matter, and rulings are built upon what has actually occurred.

If the father repents and wishes to rid himself of unlawful earnings, he may choose the appropriate method for that. We ask Allah to grant us all sincere repentance.