Is the husband's father entitled to enter the marital home, search it, and quarrel when the doors are closed, knowing that the house is owned by the husband and was bought with his private money?

The husband's father has no right to enter his son's house without his permission, especially if he resides in another dwelling. Entering someone else's house is not permissible except with permission, whether the owner is a proprietor, a tenant, or a borrower. Even if the father is a mahram, if he does not live in the same house, he should not enter except with permission if the door is closed. This differs from the issue of a father's right to his son's wealth. The wife has the right to keep her privacy from others and can refuse to live with her husband's relatives in the same house due to their potential awareness of her situation. Nevertheless, the husband must honor his father, be kind to him, and avoid anything that displeases him as much as possible, owing to the great right of the parent.