Scientifically speaking is it possible to become so used to disappointment that you are no longer affected by it?
I notice my partner and close friends/coworkers get absolutely crushed when something disappointing happens. What made me think of this was today something that I was planning fell through and people around me kept asking if I was ok and saying how they would have been so mad. I legitimately didn't give a fuck, I just adjusted my plans and looked for things to fill up the free space created by the lack of that project in my schedule.
Maybe it's because I grew up with a notoriously flaky mum so I'm used to things suddenly not happening at the last minute.