Some women would do things like to get back to you.
I don't know if it's so much to get back at you as to level the playing field, and avoid just feeling like a cum dumpster.
Like, if it goes in my mouth, it can also go in yours.
I do something similar where I like to see if the lady will kiss me after I've been tonguing away at her inner sanctum.
It is pretty hot when the lady does creative things with your jizz.
My second wife used to rub it on her face afterwards like a facial cream, and told me it was supposed to be good for the skin.
I wonder if she would fess up to that these many years later.