Crimson Longinus
Legend
Actually, that sounds like a potentially fun (but brief) adventure interlude. Foul sorcery has ensnared Sir Ensilmore's heart! Can he break free from the enchantment, using what means of resistance are available to him within the confines of the spell? ("I have to make the Faerie Queene happy, so I'll go and squeeze tribute out of the monasteries as she asks. But, while I'm at it, I'll go visit the Witch of Eastwood to see if she has a potion that might dispel this curse. But, O, I hope the Faerie Queene doesn't ask me about it, or I'll be compelled to tell her!")
Of course, the trick is in recognizing and accepting that the feeling of love is an imposition, rather than just assuming that Sir Ensilmore will go along with it because it fits the GM's pre-scripted assumption for the way the story is "supposed" to go.
Regarding the original example, it was not spell, it was just normal love. But in either case, and regardless of whether one would find it fun, it certainly is an imposition on player's agency over their character's goals.