Why is there no marriage in Heaven?

I don't believe Jesus was saying there will be no marriage in Heaven. First of all, the issue of Jesus' debate with the Sadducees was about whether there will be a resurrection or not. The Sadducees, who didn't believe in resurrection, only asked whose wife the woman would be "At Resurrection." In other words, whose wife she would be the moment she rose from the dead. Jesus answered their question the way they asked it and said no one would be getting married "At Resurrection." Nowhere was Heaven or the New Earth ever mentioned.

Had the Sadducees really wanted to know whose wife the woman would be, Jesus would have taken them to the story of creation. He would have shown them that life and marriage was originally made to last forever before sin entered the world. He would have shown them the temporary thing God had to make to accommodate for the things sin brought about, such as allowing widows to remarry. Most of all, he would have shown them that it is part of God's plan to restore everything to its original purpose, including marriage.

Something else worth considering is the intent of Heaven and Earth and then the establishment of the "New Heavens and new Earth" (Rev 21:1).

If God's intention is to restore original creation without self-induced fault in the final move of God we are anticipating according to The Bible then what we see in The Garden is Man needing Woman. If that is the 'picture' of good creation then perhaps its going to be like that in Heaven & the New Heavens & Earth.

So what am I saying?

I'm saying that The Bible doesn't exclusively say that there isn't marriage in heaven and that the ways God created in my opinion speaks otherwise. He created man to be with woman, I think Heaven & then furthermore the New Heavens and New Earth will reflect this creation plan.

Jesus says that no one will enter into a marriage in heaven, I do NOT think he meant that there will not be a state of being married in heaven.

To be like the angels may in some degree mean eternal not changing, Perhaps to be outside time as we know it. (This is a guess as Jesus hasn't said a lot about heaven).

To be like angles can NOT mean: To be in some super spiritual state without knowledge of the fellowship on earth. (Matthew 26, v 29).

Marriage is a God given thing, pointing to the great marriage: Christ and the Church, as that marriage is holy and eternal. If this is true marriages may continue in heaven barring polygamy.

This may be the reason why Jesus said that as he did.

I assume you're refering to Mark 12:25 where it says:

When the dead rise, they will neither marry nor be given in marriage; they will be like the angels in heaven. (NIV)

First a couple of notes on context. This was the answer to a trick question from a group of Sadducees. The Sadducees were an elitist liberal group similar to the Pharisees, who were an elitist conservative group. Among their many beliefs was a rejection of the resurrection. Their question from Mark 12:18-23 is an attempt to make Jesus look ridiculous for believing in the resurrection.¹

Then the Sadducees, who say there is no resurrection, came to him with a question. “Teacher,” they said, “Moses wrote for us that if a man’s brother dies and leaves a wife but no children, the man must marry the widow and raise up offspring for his brother. Now there were seven brothers. The first one married and died without leaving any children. The second one married the widow, but he also died, leaving no child. It was the same with the third. In fact, none of the seven left any children. Last of all, the woman died too. At the resurrection whose wife will she be, since the seven were married to her?”

So back to the original question. "Why did Jesus say there will be no marriage?"

The first answer, from the Pulpit Commentary on Mark 12:18, is that if she'd been the wife of only one or all seven brothers someone it would cause problems and after the resurrection there's not supposed to be any problems.

The second answer, also from the Pulpit Commentary this time on Mark 12:25, states:

There will be no necessity for marriages in heaven. Here, on earth, the father dies, but he lives on in his children after death. In heaven there is no death, but every one will live and be blessed for ever; and therefore it is that St. Luke adds here, "Neither can they die any more." St. Augustine says, "Marriages are on account of children; children on account of succession; succession on account of death. But in heaven, as there is no death, neither is there any marriage."

¹ Remember that this was (and still is) a conservative Jewish belief. It's not something Christ introduced.