First, he writes what we can get from marriage, which is "happiness in this life and exaltation in the next." That sure does sound like the goal of every human being!
Everyone chooses their own path, with their goal always to find happiness. The prophets of God have relayed this message from Heaven that abstinence before marriage, eternal marriage, and fidelity after marriage is the way to find it! That is a promise we can trust in.
Next, he talks about choosing the right spouse. He says to "measure the spiritual level of your potential future companions" because if you marry outside the church, you will be "placing yourself in a position where you will find someday that you may have to choose between that individual and the church."
On my mission, I was shocked to discover that my mission president was paring up companionships with two strong Elders and then two weak Elders. Me, in all my wisdom, thought it would be much wiser to put a strong Elder with a weak Elder to help him out. But, President Morgan said that a weak Elder is much more likely to pull down a strong Elder than a strong Elder to pull up and weak Elder. Whereas, in a companionship of two weak Elders, one must step up to be a leader.
This translates perfectly into marriage. A strong spouse cannot marry a weak spouse in hopes to bring them up. It does work sometimes, yes, but the fail rate of both is much higher than the success rate of both.
Having the same goals is essential. Elder Hales says:
"When you are choosing your companion, make sure both of you have a desire for a celestial marriage relationship, a desire to have a companion for eternity, a desire to have a family for eternity, and a desire to live in the presence of our Heavenly Father."
As I have talked about before, desire is not merely a "wish", it is a word that denotes wanting something so much that all our actions lead to gaining it. So just saying or thinking that you wish for these things is not the same as working towards them.
Temple marriage is essential for a couple who desires to be together throughout eternity. In Doctrine and Covenants 132:15 it says:
"Therefore, if a man marry him a wife in the world, and he marry her not by me nor by my word, and he covenant with her so long as he is in the world and she with him, their covenant and marriage are not of force when they are dead, and when they are out of the world; therefore, they are not bound by any law when they are out of the world."
Many people who are married outside the temple still believe their marriage will exist in the afterlife. But this does not make sense. A marriage is a legal union that is given with legal documentation. Another legal document is a loan you receive. Does anyone argue that a person will have to pay back a monetary debt to a bank after they have died? Of course not! All legal documents become null and void to a dead person.
However, an Elder Hales says: "there is no one between the Lord and the sealer when he performs the sealing ordinance."
A temple marriage is not an earthly ceremony, it is an eternal ceremony.
An eternity is so so much longer than this tiny mortal existence. We need to make the right decisions in this life so we can be eternally happy in the life to come.