This is not a foolproof plan, nor is this a world-changing solution. I think that should be obvious. But I don’t apologize for saying, every divorce is preventable as long as both parties want to prevent it. We might stress a portion of that sentence, both parties have to want to prevent the divorce. If you will both carefully apply these things, you can prevent one. Please consider: 

1. Make divorce a dirty word. The word seems to stay beyond your vocabulary. You think to yourself, “My friend is getting a what-cha-ma-thing…” You can’t quite remember what it’s called. Divorce is a thought that never, NEVER, ever, EVER enters the equation. The only time it might be mentioned is purely for intellectual consideration, as you contemplate the realities of Scripture’s teaching on the subject. Like, “God hates divorce” (Mal. 2:16), or Jesus saying divorce is not an option, “Except for sexual immorality” (Mt. 19:9). I should also add, that if the far-off, fleeting thought enters your thoughts, know that no matter how appealing it may be—it is considered one of the worst tragedies you can live through. There is far more grief involved in divorce than you think possible. There is a reason God hates it, and even our culture has begun to recognize this. 
2. Make forgiveness THE thing. This is critical to any healthy relationship, even more so in a marriage. You’re going to hear this person shout, see this person fail, watch them do something stupid. Why? Because temporal weaknesses beset each person. They struggle, they fail, they are tempted, and they sometimes give in. When describing the attributes of the “New man” in Ephesians 4 Paul concludes the chapter with, “And be kind to one another, tenderhearted, forgiving one another, even as God in Christ forgave you” (Eph. 4:31; both emph. mine, dh). This is who you are. A kind, tenderhearted, and forgiving person BECAUSE that’s how God has treated you through Christ. 
3. Make God the center. There are shadows of success all around us. We see some people and we think because they have piles of money they are ‘successful.’ We see some marriages and we determine they are a ‘success.’ I must suggest, rather strongly, that there is nothing out that that is successful if it is not God-centered. You make piles of money, if the purpose behind your endeavor is retirement—you are no success. Marriage is no exception to this rule. You may see a marriage last decades and think, “That is a success!” If it is not rooted in a relationship with God, it is an empty shell of what it could be. Listen very carefully to the words of Solomon, “Unless the LORD builds the house, they labor in vain who build it…” (Psa. 127:1; emph. mine, dh). Stock-pile investments, stay married decades, raise well-to-do worldlians, it is all emptiness. Instead, build your home from the ground up, on the Lord Jesus Christ, and make His holy will the modus operandi in your home. Everything you do ties back in somewhere, somehow into your service to God. 

This is not a foolproof plan. I must again stress, for this to work—BOTH parties have to be 110% committed. The cliché slogan is “Marriage is 50|50,” but no it is not. Marriage is you giving 110% and your spouse giving 110% seeking the glorification of God Almighty and striving to help the other be holy as He is holy.