Here is something that may assuage an uneasiness or even a basis for misunderstanding in the scriptures.
It is obvious that the Apostles, both during the life of Jesus, and after the death and resurrection of Jesus, particularly Paul, spoke a great deal about the end of the world, and clearly yearned for the end of all things when Jesus would return. Why would that be, many wonder? Without understanding why, many modern people are somewhat obsessive about the Second Coming, and, as a result, are tempted into theological error in "over eager" anticipation.
Like many things I have blogged with you about before, one must remind one's self of the context of the times when the Apostles and first disciples lived. So here is the primary reason that the Apostles were so eager for and fascinated regarding the Second Coming.
In psychology there is a phenomenon called "compensation." It means that if emotionally or intellectually you cannot obtain something that you want very much, you transfer that longing to something else. Sometimes you are aware that you are doing it, and sometimes you are not.
We learn by reading the Bible that the Jewish people were desperately eager for their Messiah, the Savior, to come. But when Jesus arrived, many people were shocked and quite disappointed. They had hoped for a "warrior savior," a zealot, who would free them from the Roman Empire and fix all the problems with humanity in the world. Jesus seemed the opposite to this, and many disciples fell away from him when they thought he was not zealous or militant enough about worldly problems, such as the oppression and occupation by Rome.
Even those who understood the message that Jesus Christ brought, how he was indeed the Messiah, but one who was bringing the Kingdom of God to all humanity, rather than leading an uprising and fixing all worldly problems, still longed for that to happen. Thus they compensated and transferred that longing for all worldly problems to be fixed from happening "now," when the Messiah did indeed arrive, to "later," when the Messiah, Jesus Christ, returns. Rather than allow themselves to be disappointed in any way with Jesus Christ, the true believers, the Apostles and the disciples who stayed with Jesus, dedicated themselves to bringing the Good News, the Gospel, to all people, and eagerly anticipated the Second Coming as being the real time, instead of the hoped for time, when all the problems of the world are fixed by Jesus.
This is why the Apostles are almost giddy at times with hope that the Second Coming would occur soon. Rather than being disappointed that Jesus was not the "militant fixer Messiah" that many had imagined that he would be, they realized that Jesus was bringing the New Covenant, and they glorified in that, but they also consoled themselves that Jesus would fix all the problems of the world (such as the occupation by the Roman Empire) during the Second Coming!
This little insight is by no means a diminishing of the theology and the reality of the Second Coming, and the glory that will be brought by Christ (after the great suffering of the world at the end). I am giving you some cultural and reality based insight about why the Apostles, so recently in the presence of Jesus Christ himself, fervently hoped for the world to end and the Second Coming to occur soon, despite Jesus cautioning them that even he did not know when that would occur. There really is an element of human nature (the saints are all human, of course) and also the cultural context (as always) in understanding those times and what people, even the Apostles, yearned for, even as they had been blessed with being alive with the Messiah present. They transferred, both consciously and unconsciously, much of their hopes that the Messiah would whip the world into shape and fix all the problems "right then and now" onto what Jesus taught them would happen at the Second Coming, when not only would the world be "fixed," but it would indeed pass away into a new one that is perfected under God.
I hope that you have found this helpful!