The following is taken from the book What the Bible Says about Parenting by John Macarthur. It is from Appendix 2 in a section called “What Makes a Marriage Strong?” The following emphasis is mine.
Marriage for two Christians is first of all a commitment to Jesus Christ and then to each other. Satan loves to destroy marriages, and the best insulation against his attacks is a deep, profound, mutually shared relationship with Jesus Christ and a commitment to obedience of God’s Word. In the presence of that kind of commitment, I don’t believe a marriage can fail.
But to expand on that, here are two principles that strengthen a marriage. First, concentrate on being who you should be on the inside, not just on what you say, what you have, or even how you look externally (1 Peter 3:3-4)….
Everything you own will decay. Even the way you look continues to deteriorate with age. But “the hidden person of the heart” matures, develops, and grows more beautiful as we become more like Christ. If that’s where the focus of your marriage is, your love for one another will grow stronger, too.
A second principle is this: Concentrate on learning who your spouse is. I have counseled many people whose marriages were faltering simply because they had never taken time to get to know each other. It’s important to realize that no person, and no marriage is perfect. If you’re clinging in frustration to an ideal of what you want your spouse to be like, you are hurting your marriage. Abandon your idea of a perfect mate, and begin learning to understand and love the one you have….
The point is that, no matter whom you are married to, you can learn to love your spouse. The prevailing wind of contemporary thinking seems to be that love is simply something that just happens—it comes and goes. And when it’s gone, people get divorced. How foreign that is to the idea of Scripture, which does not recognize even the possibility of incompatibility between two marriage partners! God simply commands husbands and wives to love each other (Eph 5:25; Titus 2:4). The feelings of initial attraction—the high-intensity impulses—will diminish in all marriages. But when commitment is cultivated, the reward of lifelong, loving friendship and fulfillment is far more satisfying.
Remember, the essence of marriage is that two people become one flesh (Matt 19:5; cf. Gen 2:24)…. It indicates that marriage is meant to be two people diligently and utterly committed to pursuing one another in love, bonded in an insoluble union of mind, will, spirit, and emotion… Every family rests on that basic truth, and the success of the family as a whole rises or falls on the couple’s commitment to each other and to the permanence of the union.