Is it permissible for a husband to remind his wife of what he spent on her for the dowry and wedding when she complains excessively, or is that considered a form of "mann" (boasting/reminding of favors) and harm?

It is not permissible for a husband to remind his wife of his generosity to her, whether it be the dowry or other expenses, because reminding of generosity (al-mann) is one of the major sins concerning which a severe warning has been issued. It involves mentioning a favor in a way that counts it against her and reproaches her. Some scholars have stated that it is permissible to remind someone of what one has spent if one has been treated badly. We advise the wife to fear Allah and to live with her husband in kindness.