I think that so far, we've touched on the 3 main purposes of marriage, from a Biblical point of view: procreation and parenting, sex, completion. There are, though, a couple of other "minor" purposes for marriage that I'd like to cover before moving on. The first of these is that marriage is a sort of archetype for the church's relationship with Christ.
This is mentioned in scripture in a few places. In Ephesians 5, Paul writes that "29After all, no one ever hated his own body, but he feeds and cares for it, just as Christ does the church— 30for we are members of his body. 31"For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh."[b] 32This is a profound mystery—but I am talking about Christ and the church." The context of becoming one body, from Genesis 2 that we talked about yesterday, is changed here by Paul. Instead of man and woman becoming one body in marriage, the church and Christ become (via the profound mystery) one. This happens, like with human marriage, to complete us. We will be complete when we become "married" to Jesus.
So what does this marriage look like? Well, like the metaphor it is. We won't have a minister asking if we "take this Savior." Besides the fact that, well, believers have already said that particular "I do," marriage as we know it is not a Heavenly concern.
The scriptural metaphor is similar in purpose to yesterday's topic: completion. We will be completed through our "marriage" to Jesus, and this completion is promised to come in the day of Christ Jesus - i.e. when we are with Him forever. The completion that comes from marrying here on earth presents a glimpse of the completeness we'll have in eternity.
There are other passages that talk about the church being the bride of Christ: 2 Corinthians 11:2, Revelation 19, and Matthew 22 to name a few.
God loves us, and loves us enough to send His own son to redeem us from our own sinful choices. He also loves us enough to provide, here on earth, a glimpse into eternity by giving us mates who complete us: not perfectly so, as only God can do that. But we understand a little of what Heaven will be like when we understand that God has provided for experiences that, in a finite world, allow us a preview of forever.