In the ancient Hebrew betrothal ceremony the groom would visit the family home of the bride. Even though the marriage was arranged between the fathers, the bride still had the right to refuse. The groom would arrive and the family would gather in a separate room within hearing distance. The groom would pour a glass of wine for his future bride and if she set it on the table she was refusing the marriage proposal. However, is she took and drank from the cup she was accepting the proposal. The groom would then announce out loud: "I go now to prepare a place for you, I will come again and will take you to myself, so that where I am , there you may be also." He would then go and build an addition on his family's home and when it was completed to his father's satisfaction he would return and the marriage would begin. In John 14:2-3 Jesus uses the language of the marriage proposal to announce to his closest followers that his going is not an abandonment but is part of a greater proposal and a deeper relationship. There are many dwelling spaces (many rooms) in the Father's house. There is room for everyone.
Jesus leaving (that is his death, resurrection and ascension) is a necessary part of his purpose. In John 13 through 17 Jesus is preparing his followers for this imminent departure. He is speaking words of comfort and strength. Notice in 14:18 "I will not leave you orphaned; I am coming to you." 14:18 is another of a list of words of hope and expectation. In 14:15 and following Jesus promises the "Holy Spirit. In verse 16 this Holy Spirit is called the "Advocate". One of my pet peeves is this translation. Sometimes it gets translated "Counselor" sometimes "Comforter". The Greek word here is "paracletus" (if I got my Greek spelling correct) which literally means "one called along side to help". Helper, Counselor, comforter are inadequate translations. I want the divine Paraclete -- the Holy Spirit along side of me to help me on this journey. The point Jesus is making is that the Holy Spirit will not be sent until Jesus has completed his purpose and journey. These words should be comforting to the Disciples -- but if one does not know the "Holy Spirit" or has no frame of reference for understanding it can be difficult.
Jesus does not give peace like the world does (14:27). The world understands peace as the absence of conflict. Peace (shalom in the Hebrew) conveys the much broader concept of wholeness, completeness. Jesus does not just offer us the absence of conflict . . . Jesus offers us the opportunity to be complete, fulfilled, whole. All too often we settle for the trivial answers to life and the world's even more trivial solutions: take this pill, do this dance, drink this beverage, look like this, attend this school, drive this car, shop this store, have this life style, ad infinitum ad nauseam (Latin spelling is correct: I looked it up!). What Jesus offers, as seen in 14:2-3 and the arrival of the Holy Spirit, is a wholeness born of essential relationship. Or, to put it another way, he offers, as the way the truth and the life (14:6), the fundamental, essential purpose for which we were created: that is living life in a loving relationship with our creator and with our fellow humans.