Couple of things.
He didn't expect Adam to remain faithful. The "fall" was a reenactment of the rebellion of Lucifer. It came off as scripted by God.
I don't see anywhere in the Bible that God didn't expect Adam to remain faithful. I also don't see anywhere that the event was scripted by God. But I do see that God gave Adam free choice, as He has with all of us.
[quote[He hasn't changed his "plan", although he has made some adjustments along the way.
His "objective" for man is to place him in his restored kingdom as new spiritual creations. His
kingdom, glory, and name are foremost. We are building blocks for that purpose, not
'the' purpose.[/QUOTE]
It is true that God has a plan for salvation of mankind, but it is not scripted down to the last detail. Because man has a free choice about the decisions he makes, the plan has to accommodate all the twists and turns of man's decisions. We see those twists and turns right through the Old Testament. There were a lot of things that happened that God did not originally have in His plan, but they happened, and God accommodated for them in the development of His plan.
I might have a plan for making a banjo, and I have all the tools to make it. I get started and my bench saw breaks down, so I have to change my method by purchasing a jig-saw to do the shaping. Then the blade breaks on the jig saw and puts a large gouge in the timber of the banjo neck, so I have to throw that piece away and have to start again. That causes a delay in time. Then halfway through I am called away to an urgent job I have to do somewhere else. That causes another delay. I eventually get the neck finished, sand it down. put the fret slots in and install the frets. Then I realise that the tambourine I have bought wasn't the type that had tensioners on the sides, so I have to take it back and exchange it. Then I get the banjo finished, and have to wait again because I ordered the strings from Ebay and have to wait until they come from China. They didn't arrive right away and three weeks later I discover the courier package under a shrug next to my letter box. Once I finally get the banjo strung up and ready to play, I have the result that I planned for, but not exactly the way I had originally planned.
This is similar to God's plans. The development of the plan may not occur exactly has originally intended, but the final outcome was achieved. God did not intend the children of Israel to wander in the wilderness for 40 years before they entered the Promised Land, but it was the unbelief of the people that prevented it happening in the original timeframe, and the original people who were supposed to go there all died in the wilderness and a new generation of people actually entered Canaan. This is just one example.
Canaan was supposed to have been subdued completely in one generation under Joshua. It wasn't because of the lack of perseverance and faith of the people. Israel was supposed to have remained permanently but because the people went after idols, the land was taken away from them, and so a different direction of development was necessary to complete God's plan of salvation. Jesus was not supposed to have come into a land dominated by the Roman Empire. He was supposed to come as Messiah to a free and faithful Israel. But that was not the case.
Paul and the other Apostles expected Jesus to come back in their own lifetimes, but because of the decay in holiness and increasing heresies, the Second Coming was delayed and is still delayed, and it could be delayed for longer while there still are many cultures that have never heard the gospel.
If God had His script about what He wanted to happen, we wouldn't have had all these twists and turns and wrong decisions throughout the Old Testament and the Early Church, but we wouldn't have a race of free individuals who are able to make their own choices. Life would be like a Hollywood movie where the actors had to follow a script and be directed in every movement and speech bringing a predetermined outcome. But life is not like that.
