As much as we may want to hold onto this world, it won't last forever and our time here is very brief when compared to the eternity that awaits us.
God designed this world to give us a hint of what is to come, as he is preparing an even better world for us at the end of time.
The world to come
Guadium et spes explains this reality in the following way:
We do not know the time when earth and humanity will reach their completion, nor do we know the way in which the universe will be transformed. The world as we see it, disfigured by sin, is passing away. But we are sure that God is preparing a new dwelling place and a new earth.
What will this dwelling place be like? Will we enjoy it?
It can be tempting to think that the new Earth will not be as good as our current world, especially if we have an attachment to something or to someone.
Yet, the Church teaches that it will surpass our wildest dreams:
In this new earth righteousness is to make its home, and happiness will satisfy, and more than satisfy, all the yearnings for peace that arise in human hearts. On that day, when death is conquered, the sons of God will be raised up in Christ; what was sown as something weak and perishable will be clothed in incorruption. Love and the fruits of love will remain, and the whole of creation, made by God for man, will be set free from the frustration that enslaves it.
Essentially the new Earth will take everything that is good right now and perfect it. This is how our current world is a sign of the world to come. Whenever we recognize something that is true, good or beautiful, it should remind us of the glory that God is preparing for us:
The blessings of human dignity, brotherly communion and freedom – all the good fruits on earth of man’s co-operation with nature in the Spirit of the Lord and according to his command – will be found again in the world to come, but purified of all stain, resplendent and transfigured, when Christ hands over to the Father an eternal and everlasting kingdom: “a kingdom of truth and life, a kingdom of holiness and grace, a kingdom of justice, love and peace.” On this earth the kingdom is already present in sign; when the Lord comes it will reach its completion.
We might be afraid to leave our present world, but the good news is that God knows us better than we know ourselves and is preparing a gift for us that we will enjoy for eternity.