Never

It is madness to hate all roses because you got scratched with one thorn
To give up on your dreams because one didn't come true
To lose faith in prayers because one was not answered
To give up on your efforts because one of them failed
To condemn all your friends because one betrayed you
Not to believe in love because someone was unfaithful or didn't love you back
To throw away all your chances because you didn't succeed on the first attempt.
As you go on your way, don't give up!