I think grief is a bad framing here. In grief you eventually move to acceptance. Given how he's shown so many symptoms of narcissism and that he's been acting as an abuser towards the country, I think it's better to frame his behavior in the perspective of a narcissistic abuser. His erratic behavior looks like ego protection in the face of rejection from a victim. He's lashing out then swearing he can change, just don't leave. All he cares about is preserving his ego and power, the bargaining won't last, he'll just keep demanding more and more, pushing to return.