People that are considerate of others, to the point of putting others before themselves often end up feeling let down.
This occurs when they base their expectations of how others should be on themselves. But not everyone is as considerate as you might be. Not everyone thinks about how other people may be impacted. Sometimes people just think about themselves. They think about their own wants, needs and conveniences.
To someone who is used to putting other people first (often to their own detriment), it can be hard to accept when others won’t do the same. But the important thing to remember is that it almost always has nothing to do with you.
You don’t have to put other people first to prove that you care. It’s actually okay to care about yourself enough to put yourself first sometimes.