They will neither marry, nor be given in marriage. But there is a marriage union, for the Lamb and his wife are married, a spiritual union that is eternal. Christ and his Bride: the Head and the Body, Revelation 21:9. God dwelling in and among his people, 2 Corinthians 6:16, Revelation 21:3.
But what Jesus does not say, precisely, is that there will be neither male nor female. What the resurrection body is, exactly, is not yet known. The subject is left open, for we are yet in the body and we are, for now, in the form that we are in.
God's purpose was ever the same, 'to bring many sons to glory', Hebrews 2:10, through redemption, they being 'chosen before the foundation of the world', Ephesians 1:4.
The whole creation was a means to an end. God's purpose never was in the first man, who is of the earth, earthy, 1 Corinthians 15:47. The Tree of Life was in the midst, in the beginning, Genesis 2:9. The first, earthy, humanity did not partake of it. And, after the transgression, was prevented from ever doing so, Genesis 3:22.
God's purpose ever was 'in the second man, the last Adam, the quickening Spirit, the Lord from heaven', 1 Corinthians 15:44. And ever was in sonship, through redemption, Hebrews 2:10, in a new creation . . . .
. . . . for, 'old things are passed away', 2 Corinthians 5:17.
'Behold, I make all things new'.
Additional (given as comment, below)
The creation is an expression of whom and what God is. And in it all we can see (if we have an eye to see it) his ultimate purposes, already expressed, but not yet spiritually fulfilled.
In his wisdom, God knew what created creature (serpent, woman and man) would do, It was inevitable. But, despite this, Deity, in unanimous counsel, determined redemption in foreknowledge.
For God's ultimate desire and purpose was to share his glory with sons, corporately, in one body.
This, I find truly breathtaking. The love of God determined to share Himself with others yet [to be] born.