Weird thoughts as soon as he has a orgasm?

OK so this is really strange and weird. I have been with my bf for years and a few years ago he cheated. Ever since then everytime he orgasms the girls name pops into my head. I have to quickly say a celebrity's name to get rid of the thought. Lol it sounds ridiculous.

I dont even know why this happens. Could it be he is thinking about her when he cums? Why else the second he cums her name pops up in my head?