I remember you posting this before.
You like him as more than a casual shag so get out of it, if it's not making you happy.
That's the terms of a **** buddies type relationship. You can't get jealous about him flirting or ****ing other women because you aren't exclusive.
And there are plenty of men out there, so you don't need him.
Also, it's nothing to do with whether you're satisfying him enough. He's not invested in you in a romantic sense. That stuff doesn't matter to him. It's only sex.