Is the fiancée sinful if she does not help her fiancé repay a usurious loan with which he bought a house, or is she sinful if she helps him repay it?

It should be noted that the suitor is a stranger to his fiancée, and nothing is permissible between them except what is permissible between other strangers. Usury is one of the gravest sins and is considered a declaration of war against Allah and His Messenger. Its perpetrator must offer sincere repentance. As for assisting this man, if the gift meets all the conditions, then helping others is commendable unless it involves corrupt intentions or malicious purposes. If it does involve such things, like winning over the heart or falling into something forbidden, then it becomes impermissible.