You just said here they they're both sexually satisfying each other. As I see it there are two relevant definitions for sex:
1) Reproduction.
2) Good feelings and intimate social bonding involving our sexual organs. The brain is a sexual organ.
Just because he takes the sexual tension her domme creates and later flogs his dolphin doesn't mean that his later satisfaction from masturbating isn't connected to the former.
I think he's confusing the two definitions.