Honestly, I never imagined I might feel at least a little bit sad for the girl and her spirit. A little, mind you, but it was still enough to register in my emotions. But it's as the prince said... Had he attempted to guide her better when things were obviously not going the way she had intended, things could have ended up better
Now her spirit that just wanted to help her is gone and they gotta lay in that nest they created together.
At the very least, the general lore around spirits is either they're very young or very old. The very old type tend to not really consider the feelings of those lower beings to them. I dunno if that's how this worlds spirits are, but given how it all turned out, I'm going to imagine he took and interest in the girl but remained a bit indifferent to the feelings of the other humans, which allowed her to go out of control and him not really consider it a problem. Once he realized he done goofed, it was too late.