Is it permissible for the husband to divorce his second wife, whose family stipulated the purchase of an apartment in her name before the marriage, and who refuses to move into the apartment and demands more money from him despite their prior agreement, while he fears not being fair between her and his first wife?

The dowry for the second wife is the apartment registered in her name. By your entering into marriage with her, the full dowry became her right. The promise that the apartment would be part of your estate upon your death is not binding on her. If you wish to divorce her, hand over the apartment to her along with all other rights of a divorced woman. We advise you to strive for reconciliation and to live with her in kindness. If the wife agrees to a lesser division, there is no harm. If you are unable to reconcile, there is no harm in divorcing her, provided you fulfill her rights.