The fulfilment took place in the first century.
If one is going to teach "The Scriptures"... then teach "The Scriptures"
Colossians 1:23New International Version (NIV)
23 if you continue in your faith, established and firm, and do not move from the hope held out in the gospel. This is the gospel that you heard and that has been proclaimed to every creature under heaven, and of which I, Paul, have become a servant.
1 Thessalonians 1:8New International Version (NIV)
8 The Lord’s message rang out from you not only in Macedonia and Achaia—your faith in God has become known everywhere. Therefore we do not need to say anything about it,
Romans 1:8New International Version (NIV)
8 First, I thank my God through Jesus Christ for all of you, because your faith is being reported all over the world.
Romans 16:19New International Version (NIV)
19 Everyone has heard about your obedience, so I rejoice because of you; but I want you to be wise about what is good, and innocent about what is evil.
"The END" that Jesus referred to in the Olivet Discourse was the end of that era, which included the thrust of the good news about Jesus and the Jewish system.
Jesus said He came to fulfill. And fulfill it was.
Thus, the obedient Jewish Christians left Jerusalem with the shirts on their backs and were henceforth cared for by Christ. Following this, the Romans came in and, according to Josephus, butchered the Jews.
Watchtower refuses to teach "the Scriptures"... they are too busy empire-building on a foundation of false doctrine.