I wonder how much of EP40's issues are from being a Kessel kinda guy. In that I mean he's not a team's centerpiece, a guy you build around, the guy you lean on all night, every night, etc. A guy who wants to just quietly do his own thing and be left alone.
It's probably a combination of a bunch of things tbh. Nagging injury (looked godawful in the 4 Nations), a battered ego after the months-long circus played out in the media and to the public (with the POHO/GM both saying anything's possible when asked whether EP40 was on the block), and probably a bridge burned too badly to repair in the end.
It would be very funny for the Canucks to lose all of JT Miller, EP40, and then Quinn Hughes in the span of a couple of years though. EP40 is Hughes' best friend, so if/when EP40 is dealt, I imagine that'd be it for Hughes' chances of sticking around--either by asking to be dealt or refusing to re-sign in a couple years.