The Lord is not slow in keeping his promise, as some understand slowness. Instead he is patient with you, not wanting anyone to perish, but everyone to come to repentance. 2 Peter 3:9
As human beings we get upset, angry, disappointed, for circumstances turn out to be different from that which we need as a response.
God moves in his own time, not ours; but when we find ourselves under pressure, crisis makes impatience increase and despair suffocate us. We do not understand that He has the time established to send us his answer, for He is never late.
He knows our ending, but He waits for us to go beyond and come out of the process as soon as possible, so He gives us what He promised. For during that time our character is transformed, submitting the will, the soul and the emotions, which is totally necessary for the blessing to be able to remain.
It would be unfair on his part if He blessed us just to please us, knowing we are not suitable for being blessed. His love is so great that He suffers through our process, but waits for the change because He does not want anything He gives us to be lost.