I have no idea of the reasons why he doesn't seem to want Hart. Maybe Guardiola doesn't feel Hart's capable of playing the way he wants him to, maybe Hart doesn't want to play that way or isn't willing to listen/change, maybe Hart has an attitude problem, maybe Guardiola wants him to learn under Bravo for a season or so and Hart doesn't fancy that as it might cost him his England place, maybe they've had a fall out etc. We can all hazard a guess as to why but none of us really knows for sure.
Ultimately though, it's the manager's call and there's not much point chasing Guardiola all this time and then not giving him the tools he wants for the job.
At the end of the day I support the club, not individual players, so if Hart's stays, I'll happily continue to support him, if he goes, I'll happily support whoever replaces him. I suspect there'll be more fan favourites (rumoured to be) leaving over the next 12 months or so and no doubt there'll be similar angst each time but we have to trust/hope that the manager's decisions take us forward as a club. I suspect that they will.