Unmarried couples need a system for managing their money. Basically, there is no right or wrong way to do it. It is important that each couple finds their own individual way to bear all the costs together. Taking out a loan should also be decided jointly by both parties. There are often arguments about finances.
However, this can be avoided if these important things are clarified when you move in. The optimal solution depends on various factors. So it depends on the earnings of both partners, whether children have to be taken care of and how much financial independence you want to keep.