Commitment in marriage and commitment to the true and living are God intimately related to one another.
These days many are without commitment in marriage. We see divorce rampant in society. A couple gets married and then when difficulty comes along, or when they have a patch during which they find that they disagree on important family issues, or when each sees that there are many traits that one another had that they didn't recognize before marriage, then they divorce one another.
Without commitment a marriage cannot endure. The tree planted with the couple falling in love and marrying one another is cut down and cannot produce the eventual fruit of eternal life, at least not eternal life with one another.
This need for commitment is not just a fundamental part of marriage, it is a fundamental part of true religion.
Consider John 6, where Christ teaches his disciples that if they don't eat his flesh and drink his blood they cannot have eternal life. He does not explain that he is referring to the sacrament, and his disciples are clearly somewhat stunned at his teaching. We read:
John 6:60 Many therefore of his disciples, when they had heard this, said, This is an hard saying; who can hear it?
The result is two fold. On the one hand we read:
John 6:From that time many of his disciples went back, and walked no more with him.
Those disciples were not committed. They may have had a testimony, but they weren't willing to stick it out when the going got rough.
But we also read:
John 6:67 Then said Jesus unto the twelve, Will ye also go away?
68 Then Simon Peter answered him, Lord, to whom shall we go? thou hast the words of eternal life.
69 And we believe and are sure that thou art that Christ, the Son of the living God.
Christ could easily explained to those who left that he was speaking of the symbols of the sacrament. Being the Son of God, he cannot possibly fail to recognize that they are misunderstanding him. But he doesn't correct the misunderstanding. He is testing their faith and commitment.
Joseph Smith taught:
"I have tried for a number of years to get the minds of the Saints prepared to receive the things of God; but we frequently see some of them, after suffering all they have for the work of God, will fly to pieces like glass as soon as anything comes that is contrary to their traditions: they cannot stand the fire at all. How many will be able to abide a celestial law, and go through and receive their exaltation, I am unable to say, as many are called, but few are chosen. (Jan. 20, 1844.) DHC 6:183-185"
This teaches us something interesting. The commitment that God wants of his saints in marriage is the same thing that will get us through to a celestial law.
Those who will "fly to pieces like glass as soon as anything comes along that is contrary to their traditions" echo the weakness of those who head for the divorce courts when things becoming challenging in marriage or when their spouse turns out (as all do) to have some trait or other they didn't expect.
It also tells us that as we, in time, approach and begin to learn about a celestial law there will be things that violate our traditions. Will we remain true? Or will we head to the spiritual divorce court, and immediately cut ourselves off from the church instead of seeing it through? Will we go to pieces like glass, or will we instead answer as Peter did: "to whom shall we go? thou hast the words of eternal life."