The Sadducees did not believe in the resurrection and life after death, so they tested Jesus. In Jewish law if a man died without leaving an heir, his brother had to marry his wife and conceive children who would receive the father’s inheritance. They proposed that seven brothers all married the same woman because none of them conceived any heirs. So they asked whose wife will she be in heaven? Jesus said there is no marriage and giving in marriage in heaven.
Why no marriage in heaven? Is there no sex there either? Isn’t that a loss? The issue for the Sadducees was that marriage and sex were necessary to maintain the inheritance. It is all because human life is finite; everyone dies at some point. So children are necessary for maintaining the continuity of life. But sex also provides a physical union that complements and supports the spiritual union between the man and the woman to keep the family unit strong and able to provide the ideal support for the maturing children. In this process, they become spiritually one as described in Genesis, and the sex between them facilitates and builds the development of this spiritual relationship.
As to the need to perpetuate life, nothing dies in heaven. We live forever there, so there is no need to perpetuate the species there. But also when Dr. Richard Eby, as a physician, was in heaven, he inspected his heavenly body and saw it was translucent. He was able to look through his body to the white flowers behind and beneath him. This did not seem strange to him but perfectly normal in his heavenly outlook on things. He also looked through his transparent abdomen and chest and could see no bones, ligaments, vessels, organs, or blood. Also he had no genitals. So the reproductive part of sex is unnecessary in heaven, but also, without genitals, sex is impossible.
But since sex is so enjoyable, how is it possible to enjoy heaven if we can’t have sex any more? The answer is in the other benefit of sex, namely, that of the physical union of the man and the woman building and supporting the spiritual union between them. This spiritual union becomes preeminent in heaven. The eyewitnesses to heaven report that heaven is all about love and relationships. God’s agape love permeates everything and all relationships there. The love you have for someone here will be so much greater there that the absence of sex will not be a concern. The oneness we will experience with others there will surpass what the physical union of sex provides here. Since there is no sin in heaven, nothing will hinder your relationships and they will be enjoyable beyond what is possible here where sin is so prevalent. Your relationships, especially the deep ones cultivated on Earth, like that between husband and wife, will be greatly enhanced in heaven. The need for physical sex will be replaced with a much greater enjoyment of each other in a spiritual relationship; much deeper and more profound than any we have here.
So according to both Jesus’ testimony and that of eyewitnesses to heaven, sex will not be missed because the relationships sex facilitates here will be so much greater there. Many witnesses were able to meet couples there, e.g. grandparents, who were continuing the intimate relationship they had on Earth. The parent-child relationships there are stronger also. So you can look forward to better relationships there with more love than you have known here. There won’t be marriages there, but the relationship you will have with a spouse there will be superior to any you could have had here. The love relationships you have will not be lost, but enhanced and much better than they are here and possible with many other persons. If you have had two Christian spouses, you will have great love relationships with both of them.