to disappoint you
I thought I would disappoint you.
Désolé de te décevoir, mais tu te trompes.
Sorry to disappoint you, but you’re wrong.
— Suzhou River (2000)
Ce serait le dernier à te décevoir.
He would be the last person to disappoint you.
I hope I don't disappoint you.
Je suppose que je ne voulais pas te décevoir.
I suppose I didn’t want to disappoint you.
I don't want to disappoint you.