Helpful, when someone goes to a Rav for counseling and advice, even if they go for months, do they divulge that a potential mate? Why on earth does someone have to divulge that they went to therapy to help them through a difficult period or a bad time in their lives? Who’s business is that? No one’s business at all.
Now if the young person choose to speak about the rough patch itself, that is another ballgame and that all depends if that part of their life will have an effect on the couple and their future.