Puppy spends the night with his friend Rex over valentines day. 

Also this was written before I wrote the Christmas story, which is why the new character introduced in that story, Suzi, isn't in it, despite living with Rex (I didn't want to rewrite the whole thing, I could have added a subplot with Suzi and Rover but I'll leave that for another story). Maybe this story happens before the latest Christmas story, being the valentines day before last Christmas.