Oh, this is a fun one!
Jules would probably answer similar to how Motif answered, though maybe with a "I dunno, it's [a gentle and relaxed "f*ck]-ing a thing that exists, I guess..."
Katherine does not know what Valentine's day is, and would find it kind of childish.
Bob and Brenda have no idea what it is either but would be INCREDIBLY game, knitting pink and red sweaters, throwing their loved ones dinner, the whole nine yards, and mostly in a friendship/platonic fashion. They are decaying zombies, I don't see them being particularly romantic, per say.
