Is it permissible for a woman to give her money to her fiancé before marriage for him to invest in a business project?

There is no blame upon you for lending or partnering with your fiancé with your money, provided that you are among those who are authorized to dispose of their wealth. It is preferable that one of your male mahram relatives handles this. We draw your attention to the fact that a promise of marriage or engagement before the marriage contract is concluded does not permit something forbidden, such as khalwa (private seclusion), touching, speaking, or looking.