I thought it wasn't in the vendor but it's there, in the bottom before the valentine set. Just thought I should post it here since I remember seeing people (me included) thinking it wasn't available anymore since they removed the gift box.
Saw it, and bought it for all characters (even though five can't use it, stupidly thought they could still claim the style even though can't use it ) Still hoping next year they will add Cupid-inspired styles for the other weapon-types (heart shaped shield, boxing gloves with lips, that sort of thing)
I did the same thing even though only 2 of my characters actually use a bow, you just have to place a SP on bow and they'll be able to consume the style.