I promise you, we all understand and feel the same way to a degree. You aren't alone.

[ even as someone who would really have to think about staying here voluntarily if given the choice, Steven still misses Hoenn. despite how much he enjoyed travelling and learning about new places, the region is still home for him. ]

It's unfortunate, but you may never get "used" to people leaving. You can certainly accept it as a reality of this world, but it doesn't necessarily get easier. The best way I've found to combat it is to simply live in the moment. Try not to worry about what may come tomorrow, but focus on the relationships you're making right now.