Why DC Just Cancelled Jared Leto's Joker Movies
3. A Joker/Harley Film Wouldn't Have Been Appropriate
To longtime readers of DC Comics (and even to longtime viewers of DC Animation), there is only one thing to describe the relationship between Harley Quinn and the Joker as being: abusive.
Although Quinn's origins have changed over the years, one element tends to remain consistent; she's a brilliant psychiatrist who's assigned to Arkham to profile the Joker. Over the course of their sessions, the Clown Prince manipulates Quinn into falling in love with him, breaking him out of Arkham, and into becoming his new accomplice. At no point does he illustrate a hint of 'love' for Quinn, using her merely as a means to an end and repeatedly mistreating her in most depictions, to the point of almost killing her in Dini and Timm's seminal Batman story, Mad Love.
Except, in Suicide Squad, the relationship was flipped completely on its head. Instead of there being an abusive dynamic, David Ayer elected to depict the pair almost like a modern day Bonnie and Clyde, resulting in an awkward fandom that began to idolise their relationship with poorly intended makeup tutorials and fan-fiction.
When it was first announced, The Hollywood Reporter referred to the project as "When Harry Met Sally on Benzedrine", which couldn't possibly be further from how it's seen in the comics. Factor the precedent established in Suicide Squad, and it was clear to see even back then that a Joker/Harley rom-com was a bad idea.