Joker is warring with trying to enjoy married life and his inner repulsion of personal attachments.
This is the sequel to Smile (with Teeth). You should definitely read that one first. Same warning apply.
From the beginning of their relationship, the Joker insisted that Harley Quinn was just a bit of fun to him. This story examines the beginning of that relationship, and continues on through the many ups and downs to see if the Joker can finally admit that Harley means more to him than that.