I have copied an excerpt of a letter to Rebbetzin Esther Jungreis. See the link for the entire question; she doesn’t seem to have responded yet.
. . . Now, here is our dilemma: Are we obligated to tell the shadchan, the girl and her family? My husband and I are conflicted. I say “yes”, but he argues “no”. According to him, the moment we say the words “Bi-Polar’ we terminate all his chances of a decent shidduch. Moreover, my husband feels that since he has been totally well since he started on medication (and that has been five years now) there is no reason to announce a problem which is no longer present. He also argues that if the girl and her family find out about this and as a consequence she refuses to see my son, it will devastate him and he will regress. On the other hand, I am not comfortable leaving the situation as it is. To me, it borders on deception. My husband and I have been literally fighting about this. The conflict has destroyed our shalom bayis and I really don’t know what to do. I was thinking that we should consult his Rosh Yeshiva, but my husband pointed out that the Rosh Yeshiva is the first person people turn to when they seek shidduch information, and if he is made aware of this problem, he will have to reveal it – and the same holds true of the Rov of our shul, so as you can see, we are in a terrible bind.
I have a few comments. First of all, it’s sad that no one thinks that the son has any say in the matter. How does he feel about deceiving his future wife?
The boy’s father is also being naive about the illness. Medications cease to work or need to be adjusted, and patients often decide to stop taking them.
On the one hand it’s sad that the parents are so sure the shidduch will be broken once they tell. It would be nice if the girl’s parents would be willing to overlook this, although one could certainly understand some reluctance on their part.
The parents posing the question need to ask themselves two questions: 1) Do they want mechutanim whom they believe would refuse a shidduch for their own daughter because of a treated mental illness and 2) How would they feel if the shoe were on the other foot? Would they want parents of a potential shidduch for one of their younger, healthy children to hide such information?
See Brooklyn Wolf for further comments on the letter.