What positives do you get from this relationship?
Seriously ask yourself that question. Try and answer it as honestly as you can.
You are supposed to be his partner not his mother or his babysitter.
He games all day, has inappropriate relationships however possible, doesn't work, pulls the "I'm depressed" card any time he has to face consequences or is caught behaving poorly.
(((gently)))
He is a child and a very irresponsible one at that. My 17 year old son sounds more mature that your WBF.
At what cost are you willing to continue to be the only adult in this relationship?
What you allow will continue.
You deserve better and in the end the only person you can change is yourself.
Good luck.