Here are some points we can gather from the story of the first romance:
1) Marriage must be pretty important to God. He created marriage before any other institution, including the church or the government. It's foundational to any society or nation, and moral decay and collapse always start with the undermining of it.
2) Marriage is not a man-made institution, flexible and malleable to the whims of majority rule. Marriage is not defined by the state or by any group of people, but by its Creator.
3) It's not just a contract or a gathering together of two individuals; it's the permanent union of two into one. Adam said his wife is “bone of my bones and flesh of my flesh” and God said they are “one flesh” in vs. 24. C. S. Lewis pointed out that divorce is not the dissolving of a contract so much as it's an amputation of one’s limb. Just like amputation, it might in extreme circumstances be necessary, but it's never desirable and should always be the last resort. Do you begin to see why God hates divorce so much?
Now let’s talk about nudity for a bit. The last verse in the chapter says that the man and his wife were both "naked, and they felt no shame.” This is talking about more than physical nudity. They could be completely open and honest with each other. There was no shame because there was no guilt, no fear, no secrets, and no hidden agenda. This, of course, would change in the very next chapter. This is why (in general) nudity should be restricted to marriage, not because there’s anything wrong with the human body (that would be asceticism), but because sin has entered the picture. The reason we need clothes (and animals don’t) is not just because we need protection from the elements, but because of what happens in chapter 3. But we can't move towards the goal of a perfect marriage without understanding what his original design for it was/is. This is what he created marriage to be, and it was sin which ruined all of it. But as he works in our lives to restore us, that's his goal: Total intimacy, total trust.
This applies to emotional “nudity” as well: Be careful of “exposing” yourself to people who aren't trustworthy; remember that we live in a fallen world with fallen people.
On a more positive note, I'd be remiss in failing to mention that when Paul (under the inspiration of the Spirit) was looking for picture of our relationship with Christ, he repeatedly pointed to marriage (we are the “bride” of Christ). The Lord Jesus is the One whom we can completely trust, without any guilt, fear, secrets, or shame. He's as close as our heartbeat, as close as the breath on our lips, or at least he'd like to be.
Lord Jesus, thank you for claiming me as your own. Help me to be completely open and trusting with you. Help me to be the spouse you want me to be, and help me to be sexually pure with the one person you desire me to be “one flesh” with.