it's actually not as odd as you may think. one the one hand it's worth noting and simply accepting the fact that life is full of unexpectedness so just about anything can come up out of virtually nowhere and drastically alter someone's level of availability
on the other hand are those who commit themselves to too many things at once, be it unintentionally or because they're very confident in their ability to handle a number of things only to be able to manage just a small few. I've been guilty of this in the past.
In most cases though a person usually doesn't do so with ill intent and sometimes it is a bit of mismanagement on their part and in the few rare cases someone is doing it intentionally there's usually some other behavioral pattern that gives hints into whether or not that'd be the case. think group projects and the one who purposefully makes tons of excuses as to why they can't help versus the one who actually has a bunch of things going on and thus can only contribute a little bit here or there
i think this is why generally i try to give folks the benefit of the doubt and in cases of myself or another having a busy schedule find means to compromise so that everyone is ab;e to work at a pace that wont impede in/on other things.
also gotta note this post seems really vague so idk the specifics of whatever circumstances you're in but i hope you won't hold a grudge as to whatever may (or may not who knows) have happened
