I think you hit it on the head with your explanation. Being cured doesn't make us immune to relapsing or failing god, it wouldn't be right to think that God got it wrong. I think that I simply let too much sin hence void of God in to my life which prevented me from being able to approach the throne of God boldly. Instead of being able to run to daddy (God) for his protection and forgiveness I had to run away because I wasn't willing to let go of all the other sin that I'd allowed to enter my life. Hence, no power to stand against satan under his temptations. The way out that God promises was blocked by sin.

God is faithful. He will not let you be tempted beyond what you can bare and when you are tempted he'll provide a way out so that you can stand under it.

God WAS and IS faithful, I wasn't..

I hope that this helps and of course you are in my prayers.