But even that spirit just guided villagers into getting together. Even if it fed on love, the spirit was not capable of that emotion.
IDK, it seems to me that you kinda have to understand love to help others find it.
Spirits seem to be driven to express their titular emotion. Cole (Compassion) is obsessed with showing compassion for others and acting in accordance with his name. Faith encourages and rewards the faith of others. Wouldn't a spirit of romantic love encourage others to find love?
But yeah, spirits don't necessarily understand emotion, but they are certainly capable of experiencing it. Cole is constantly baffled by what he's feeling. Solas says that conflict drives spirits mad, but would romantic love be at odds with a spirit who already embodies that? Then again, if the person the spirit loved disappointed them, the resulting anger might corrupt that spirit into jealousy. I'm not sure I'd want to be in a relationship with a jealousy demon. Although the idea of a romance quest that involves killing your LI is definitely angsty.
In any case, thanks for allowing this little intellectual exercise. I doubt they'd pull the "spirit became mortal" more than once, so that's all it is.