Intensifying the psychotic passion between these two is the fact that Harley is not just The Joker’s girlfriend, henchwoman or arm candy. Far from it, the two are equals. Speaking to Screen Rant, Costume Designer Kate Hawley analysed the relationship in the following way –

‘There’s this obsession and this relationship [between Harley and Joker] that… it’s almost like two alpha males, you know? You never feel Harley’s done under in a way, it’s been beautifully interpreted by David in her dialogue, that she’s such an amazing, strong character and they’re like two alpha males. They go out and the games they play with their victims, it’s like cat and mouse.’

—  CINEMA eZINE
PSA

With Suicide Squad coming out, I’ve been seeing a lot of HQ love (which is awesome), but what’s not so awesome is the amount of people I see romanticizing Harley and Joker’s relationship. This whole, “I want to find a Joker to my Harley” or “I want a puddin’ too” is really… not okay. The Joker abuses Harley.

They are not an example of a healthy relationship. 

Harley has stated in the comics more than once that she’s his victim. Their relationship is not cute, or romantic, or healthy in any way shape or form. Abuse should really not /ever/ be romanticized, and I really hate to ruin anyone’s fun, but please. Please. Stop putting an abusive relationship on a pedestal of ‘I want a relationship like this someday!’, etc, etc.

 Their relationship is not even supposed to be vaguely OK. Please stop making it out to be this romantic dream relationship. Because, uh. It’s not.