I am redating this post because it is getting still getting some active discussion, and has been visited by Dave Baggett, a co-editor of Harry Potter and Philosophy and C. S. Lewis as a Philosopher.
How would a compatibilist analyze the case of an effective love potion, which the Hasker passage appeals to in his reference to Harry Potter? In the case of Voldemort's mother Merope, she cast a spell on Tom Riddle, Sr., causing him to love her, only to become frustrated by the fact that the love produced by the potion was compelled. So she stopped using the spell, and he dumped her.
What accounts for the frustration and disappointment with a love compelled by the one being loved?