I also found reading about attachment (look up Bowlby's attachment theory) really helped me understand a few things about some of my relationships, which includes how I get on/feel about different clients.
+1 and I can recommend Natalie Lui's trilogy, "Mr unavailable & the fall back girl" in particular is a good one. She's got pod casts on sound cloud. That can help as an immediate quick fix to stop obsessing over someone.
We only see snippets of clients & not the full picture, they can be whoever they want to be in that hour.
Shit skids in the underpants visualisation helps put me off
, imagine them walking around without the aid of toilet paper & having to use their underpants, I think most men have done this at one time or another