Are you saying that we HAVE to tell our SOs about every single thought that crosses our mind in order to be honest? I do not think so but I want to make sure.
Absolutely not. But... if I have a thought and I want to express it, I am being honest (and I think there is a way to do that respectfully and not.) If I do not express the thought because I have anticipated someone else's potential reaction, or I fear another's reaction... I am not being honest, one, I am not respecting myself, two, and I am not giving the other person an opportunity for THEM to act or respond, honestly or otherwise. I've taken it completely out of their hands.
Heather not expressing her thoughts about Leo was her choice, because of what she decided was respectful or not. That's cool. Got no problem with that. But if Heather held back because of the way she thought her H might respond... you have another issue.
