I don't think anyone has the "right" to know your medical history if you don't feel they should. So long as it has no bearing on their health. So unless there is something like an STD/STI sure, he doesn't have the right to know...
That is my firm opinion, but we do live in the real world, and the truth is, if you are pre-op you will be found out eventually. That could also be a very big risk to one's health as men have been known to be very violent in this circumstance.
I don't think she was in the wrong per se, but I also don't see how she can really feel bad about what happened anyway, after all what did she expect would happen? She got in a bad situation but, enjoyed her time in love, more than she thought about her own safety; there was no way it was going to end well.
I don't see anything wrong with stealth, but you have be smarter about it. The way culture works, it would be an incredibly rare thing for a partner to find there is a penis when one wasn't expected and be indifferent to it. That is just the way things are, and they are unlikely to change soon.