Every relationship no matter how religious the couples involved are needs: communication, chemistry, trust (built over years of faithfulness), maturity and most importantly the fear of God.
Every man and woman who hope to make something good out of a relationship want a faithful partner.
But being faithful in our world tends to get harder and harder with cheap sex and naked people all over the place.
To be faithful to our spouses therefore we need first of all to be self determined and make the decision not to cheat on our spouses. After making the resolve the following steps if taken can be helpful:
1. Be a man/woman of your words (do not live a life of constant promise and fail)
2. Do not keep secrets from your spouse
3. Thouroughly extinguish old flames and do not attempt to rekindle them
4. Maintain friendship and romance with your spouse
5. keep your friends and your spouses friends at a reasonable distance
6. Maintain appropriate boundaries with coworkers
7. Appreciate your spouse and their efforts no matter how little
8. Be a flirt only with your spouse
9. Admit your faults when you are wrong and work on your weaknesses
10. Resolve your problems together do not bring in third parties
11. Have a satisfying sexual relationship (ensure you engage in sex in marriage not as a duty but as a truly satisfying leisurely activity) where both party aims at satisfying the other
Having said all the above pray and always put God first, only God can truly help you to build a good home.