She was disappointed not to be chosen.
She was disappointed not to be accepted into the club.
He was disappointed with his exclusion from the England squad.
You should have accepted that. I’m disappointed in you.
Once again he was disappointed in love.
I’m disappointed in you ─ I really thought I could trust you!
To say we are disappointed about this is putting it mildly.
I was disappointed to find that they had left already.
I’m disappointed (that) it was sold out.
I was disappointed that Kluge was not there
But then to be let down like that, oh it’s so unfair!
He trudged home feeling lonely and let down.
Sadly, the film is let down by an excessively simple plot.
Don’t let down even if the going is good.