From i gather here the therapist is just some collateral damage in the dangerous and intricate 'game' playing by those two characters. Clark finally realized that he was in the wrong bc their deal got out of hands, the killer developed a morbid obsession towards him after being 'seduced' by clark in the swift, manipulative and subtle way. well that was the outcome as what he wanted in the beginning but only to realize that he has made a huge mistakes when someone else got dragged in their game

Just want to ask, why would Clark end the relationship with Alex if he knows that Alex can end the life of the therapist guy (who he considers a friend) at any point?
Is he up to some cheeky shit again?