Is it permissible to borrow from one's fiancée to complete the dowry amount and repay her after marriage?

There is no objection to borrowing from the prospective bride or others for marriage or to meet needs, as long as the loan is non-interest-bearing, and the borrower intends to repay it. The borrower for the purpose of marriage is aided by Allah, for Allah Almighty says: "If they should be poor, Allah will enrich them from His bounty," and because the Prophet, peace and blessings be upon him, said: "There are three whom Allah has promised to help... and the one who marries, desiring chastity."