It's a power play. He gets to leave you and feel inflated about it like he's in control of life and you're the one with the problems.
It's a con. Don't believe it. His life is a sham because he is utterly controlled by alcohol and has lost ALL freedom.
Keep yourself safe, away from him, and when he wants to come back (very likely), know that if you take him back, he'll very likely do this again.
BJ