My H knows about my diagnoses. He and I have talked about them (for years) and how they impact our relationship. He has a DX of BP II; yet, is much more treatable and, thus, stable than am I. I have C-PTSD in addition. We are both very open with one another and our relationship is still going strong after 20+ years. (Knock on wood.)
If either of us feels the other withdrawing, we usually initiate a conversation about it. We know one another, and one another's moods, very well. We are both very compassionate toward one another.
Granted, a relationship where two are diagnosed with a condition may be unusual? It likely gets much more complicated if only one partner has a DX, and/or a history. It can get complicated, I am sure. If I were dating, it would feel very complicated to me.
I do think it's possible to reach a point of trust with another, in which sharing openly is safe, even nurtured.

WC