Is it permissible to take out a usurious bank loan to finish the marital apartment, knowing that there is no other solution to secure the money, and that postponing the marriage is difficult?

If borrowing for the purpose of completing a marriage is done through usurious institutions, then it is not permissible. This is because borrowing with interest is one of the major sins, except in cases of extreme necessity, and completing a marriage is not one of them. Therefore, it is not permissible to borrow with interest to complete a marriage. One should be patient and seek help from Allah, for "whoever fears Allah - He will make for him a way out and will provide for him from where he does not expect."