Zohn-Ha-Lok in “Unfinished Business”

Love is the most dangerous emotion of all. It produces many other emotions: jealousy, shame, rage, grief. You must learn to suppress them all, otherwise they will consume you. [later, after months of training] You are now prepared to return to the world: grief, anger, fear and especially love will never threaten you again. [A Vulcan master to a juvenile Tuvok]