I'm thankful you have a strong relationship now -- but I'm especially thankful you realize there could be dangers ahead, and you want to take steps to prevent them. A good marriage doesn't just happen; it takes work -- but it's worth it.
I could say much about building a strong marriage -- but I've sometimes summarized them in four simple points that might be easy to remember. Let me repeat them; each begins with the letter "C".
First, Cherish. God gave you to each other; you are God's gift to your spouse. Take time to express your love, both by your words and by little acts of thoughtfulness -- a surprise gift, a special time away, a favorite dinner. Cherish your wife, and let her know she is important to you.
Second, Communicate. Let each other know what's going on in your life at home or at work. Don't clam up; don't nag or only express yourself when you're upset. The Bible says, "A word aptly spoken is like apples of gold in settings of silver" (Proverbs 25:11).
Third, Compromise. The greatest enemy of love is our selfishness, but in marriage you can't always have your own way, so learn to compromise with grace. The Bible says, "Love does not demand its own way" (1 Corinthians 13:5, The Living Bible).
Finally, Christ. Make Christ the center of your lives and your marriage every day, by committing yourself to Him and His will. He is the solid foundation we need -- in our lives, and in our marriages.