It generally makes sense that a Sleuth takes +1 damage when she takes Cool damage from a Like relationship; that sort of betrayal stings ("Damage" BGS 66).
But BGS 89 ("You Hate Me but I Love You") talks about Relationships where party A Likes party B while party B Hates party A. We've got a situation like that in my game, and I anticipate running afoul of the "Damage from a Like" rule soon.
I gave one of our Sleuths a free one-point Like with the culprit of our current mystery (she friended the culprit on Facebook as part of the investigation; "Creating New Relationships" BGS 100), but the Sleuth finds the culprit distasteful at best and is not happy he Likes her. We're likely to throw down with the culprit in our next Bubblegumshoe session (and/or later on in the campaign), and by the rules it seems like Cool damage he inflicts on the Sleuth he Likes should deal +1 damage... but since it's unreciprocated, I'm not sure that follows narratively.
I suspect this an edge case where we just rule what makes sense, but I'd like to know if I'm missing anything in the book about this kind of circumstance.