My husband recently discovered that he is 52% European Jewish through an Ancestry test. He matched with a female second cousin that is 100% European Jewish. Is there a way to know which side (mother or father) of her family he’s related on?
The easiest way that I know of is to find a third person related to both of them, and see which side of the family that they are on. Given the closeness of the relationship (2nd cousin), finding a third person shouldn't be hard.
If your husband's parents (either/both) are still alive, have them take an Ancestry test.