I was fighting an Audino once...a wild one. Got it in the red, and it used Heal Pulse right before I finished it off. I felt so guilty walking away that I put Anna, my Audino, in my party and began training her immediately to fill the 5th slot, as I only had a semi-permanent team of four at the time. First move I made her learn was Heal Pulse.
Wouldn't you feel guilty, too? You've been struggling to take this thing down...both your Pokemon and the wild Audino are exhausted...it's on the verge of fainting, and it heals you instead, even though it knows what will happen next.
It wasn't that bad when it happened, but when I thought about it...I stood there for a little bit after it was over and realized what it had done.
Tabunne are worth so much EXP...but really, all they want to do is help you.