What is the ruling on taking a necessary loan from a non-Islamic bank for marriage?

It is not permissible to take an interest-bearing loan from a non-Islamic bank for the purpose of marriage, because marriage is not the only means to prevent fornication. There is also fasting, and taking medications that temporarily reduce desire. One must also keep away from sources of temptation, lower the gaze, be patient, associate with righteous people, and supplicate. Usury is a greater sin than fornication. The Prophet, peace and blessings be upon him, said: "A dirham of usury that a man consumes – while he knows – is more severe in the sight of Allah than thirty-six acts of fornication." So be patient until Allah grants you a way out, and beware of interest-bearing loans.