You can still have chemistry on screen without getting on with the person. But it just makes your job a lot easier if you don't have to gird your loins, if that's not quite the right phrase, every time you're going to do a scene with that person.
“I would say that maybe directors who act as well are easier with actors. I'm not saying that all directors have this, but sometimes you'll come across a director who sort of looks at an actor a bit like a kind of untrained horse that's been let out of the stable, like they might buck him.”