Circumstances do not change the promise!
If we focus on our surroundings or the circumstances involved in the lives of our prodigals, our faith can falter. However, we must keep our mind on the promise, because that is what is really true.
God knew about our tendency to focus on what we can see and hear. Perhaps that is why He had Paul write these words: "Finally, brethren, whatever things are true, whatever things are noble, whatever things are just, whatever things are pure, whatever things are lovely, whatever things are of good report, if there is any virtue and if there is anything praiseworthy--meditate on these things." (Philippians 4:8)
When your faith is weakened for the moment, meditate on this verse: "God is not a man, that He should lie, Nor a son of man, that He should repent. Has He said, and will He not do? Or has He spoken, and will He not make it good?" (Numbers 23:19)
Hold on the promises God has given you regarding your prodigal. It WILL come to pass!