here's what I did in D route
don't trust the peri princess but don't be hostile either, just be cautious
ask why they haven't visited the soldier who tried to assassinate us
when they bow, allow them
tell them both them and their parent weren't at fault
the unsteady stat might still appear for a moment, but as long as you do all of the above, and then choose to ask when will we see them again when they're leaving (instead of wishing them well), you'll be good ^^
good luck and just let me know if you're still having trouble!