Kira going gung-ho after Prin would've been totally A-OK if not for the fact that she was carrying a child
. Frankly, I think "running and hiding", however much that would drive Kira insane, would be the appropriate and even noble response to that situation: yes, it means sacrificing pride, but it would take real character to do that--more so, if you ask me, than going charging in. Whatever reckless thing she wants to do with her own life, I could understand that even if I still wouldn't like her attitude. What she decides to do with another life that can't have any say in it--that I have no tolerance for whatsoever.
And like I said, Kira didn't even have to repent for what she did, in Silaran's presence. Even something after
the fact would've made it more understandable.