At some point keeping secrets is not a good ideal and it tend to cause a lot of damage when the truth comes out.
But I will first say this on a neutral ground, keeping secrets or deciding to keep things to yourself without sharing is not good because whatever reason you are Keeping tend to be at risk at the end.
Keeping secret in a relationship is the worst things that will happen in a relationship and this tend to break relationship a lot.
Talking about health status if you refuse to share such condition no one will have idea what you are going through and as such the person is prone to risk.
So I think we should do well to share with people we can trust and loved once whatever we face in life.