I would amend that comedian’s line to be “insofar as unconditional love exists, it only exists for mothers and babies”. There is nothing my baby can do that will cause me to stop loving her. And unfortunately, there is probably nothing I can do to my baby to cause her to stop loving me (as many abused children can attest). But that no longer applies after babyhood. The list of conditions grows with moral culpability. If I were Eve, I would stop loving Cain.