A lot of Christians spiritualize marriage. Since St. Paul compares it to and claims it represents Christ and the Church, these Christians let their confidence in that heavenly relationship bring on an ambivalence about their own earthly one. "It's what's in heaven that matters." Others have a far more horizontal effort toward marriage. They consider adultery a calamity because it hurts spouse, kids, and others. These Christians are not ambivalent but counteract these forces by restoring romance, holding marriage conferences, and writing how-to books that we can't politely discuss on this page.
Both approaches are recognizing true things. It is all about Christ and the Church, and we do need practical help. And if we spoke of the practical goods and evils in terms of the spiritual reality, might we not sound like St. Paul? Violations of marital goodwill should not be merely assessed as a failure of spousal obligation, but a blow against the very name of Christ our Lord.
"Do you not know that your bodies are members of Christ? Shall I therefore take the members of Christ and make them members of a prostitute? Never! Do you not know that he who joins himself to a prostitute becomes one body with her? For, as it is written, "The two shall become one flesh." But he who is united to the Lord becomes one spirit with him."
I Corinthians 6:15-17
Consider that visiting a prostitute is not primarily a crime against your marriage (while it is that), but the phrase "Do you not know...?" suggests that your awareness of your unity with Christ ought be the compelling force to say, "Never". Also in this short passage the physical union "one flesh" with the prostitute mitigates against your spiritual union with Christ. Where then does your physical union with your wife fit in?
"Shun immorality. Every other sin which a man commits is outside the body; but the immoral man sins against his own body. Do you not know that your body is a temple of the Holy Spirit within you, which you have from God? You are not your own; you were bought with a price. So glorify God in your body." I Corinthians 6:18-20
Your body (in this case your sexual body) is a place of glorification of the Lord. Your relationship with your spouse is the metaphor for the glories of the Gospel and Our Lord's care and consideration. It's not that a strong emotional, spiritual, and sexual bond in your marriage does not benefit your struggle against temptation (see I Corinthians 7:1-7). But you are not just avoiding a negative assault by your deeper relationship, you are declaring a positive good. Christ your Savior is being declared by your love for your wife or husband. If you measure your actions toward your spouse by what mercies Christ has given or what obediences he ought expect of the Church, the power to set aside sin is manifestly absolute. If you are only practical and horizontal, realize that there are Gentiles that can enjoy a rewarding marriage by God's common graces. And a satisfying sexuality can be as much of a temptation to illicit behavior as the absence of it. If your marital nature is not defined by Christ's supernature, it will define itself by quantities of human gratification alone. And you must then keep adding benefits to your marriage, more adventure, romance, communication, etc. All of these are, in truth, good and valid enjoyments, and large armies usually win the wars. The Scriptures tell that "the battle does not always go to the strong" and it warns you not to trust in the "arm of flesh" or the "chariots of Egypt". These have certain powers, but sin can call you across a line that the greatest wife in the world is insufficient to bar. Remember that Eve lived in a perfect world.
Christ and the Church is the reality of which your marriage writes. Your practical efforts are not to build up your troop strength against the temptations of the flesh, but to write on your husband's or your wife's flesh a metaphor that all will say is apt. "I am the Lord," says the husband, "and my wife the elect." "I am the ransomed," says the wife, "and my husband is my Lord who purchased me." "As Sarah obeyed Abraham, calling him Lord." says I Peter. Notice St. Paul on this:
"Wives, be subject to your husbands, as to the Lord. For the husband is the head of the wife as Christ is the head of the church, his body, and is himself its Savior. As the church is subject to Christ, so let wives also be subject in everything to their husbands. Husbands, love your wives, as Christ loved the church and gave himself up for her, that he might sanctify her, having cleansed her by the washing of water with the word, that he might present the church to himself in splendor, without spot or wrinkle or any such thing, that she might be holy and without blemish. Even so husbands should love their wives as their own bodies. He who loves his wife loves himself. For no man ever hates his own flesh, but nourishes and cherishes it, as Christ does the church, because we are members of his body. "For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh." This mystery is a profound one, and I am saying that it refers to Christ and the church; however, let each one of you love his wife as himself, and let the wife see that she respects her husband." Ephesians 5:22-33