It would depend entirely upon what was being hidden and why. For me there isn’t a blanket answer.
It would also depend upon whether I somehow stumbled upon the truth forcing a conversation about the truth of the matter or whether the other person fessed up and initiated the conversation because they no longer wanted to live in deception. To me, that aspect of it would be very important.
Just for example: If he were a cross-dresser, I wouldn’t feel as much about trust being violated because I’m aware of how much stigmatism there is about this in our current culture.
It’s no small wonder anyone would be secretive about something like cross-dressing since it carries with it such a fear of rejection.
But on the opposite end, if he was having an affair with someone else when we had agreed to be exlusively monogamous to each other, that’s a betrayal of trust on an entirely different level.
And if I discovered it, that would be the end of the relationship. There would realistically be no way to rebuild trust. No one forced you to say you would be monogamous. You could simply have said you weren’t quite ready for that yet.
Instead, you CHOSE deception when you didn’t have to. There is no recovery for that, in my mind.
Being secretive about cross-dressing is understandable because cross-dressing springs from such an innate need within that person. Many aren’t even fullly in touch with why nor fully understand it.
Having an affair is a purposeful deception and indicates a complete lack of respect for another person and no respect for truth. That’s far more pathological to a relationship.
People can make accompdations for cross dressing. There are many couples who are still happily married long after the partner has confessed about it because it’s not a character flaw.
Purposeful lying (even when it not really necessary) is a character flaw and not one I would want to continue to deal with in another person.
I realize that there are relationships which survive infidelity, but personally speaking it would be a deal breaker for me.