(Disclaimer: Newbie here with zero polyamory experience).
When I read your posts, I'm not hearing jealousy; I'm hearing envy.
He's getting to have more fun than you. Example 1: He had more fun with the girl, while you got bored of her (less fun). Example 2: He only has to work "4 days" at the job, and you work an extra day that he has off.
Does that resonate? If so, maybe the solution isn't to try to find a way for him to have less fun, but for you to find a way to have more fun?