Devotion about dating
Realizing that practical steps matter, most often they want tips or steps they can take to build their relationship in Christ. (Protip: this last one is definitely not a winning approach.) At that point, one of the first things I usually tell them is that there's really no “biblical theology” of dating tucked away the book of 4:5-20. This can actually become a problem, especially because you're not actually married.
There are some rather obvious tips like praying for each other in your daily devotions, encouraging each other to read the Scriptures, setting appropriate boundaries (emotional, spiritual, and so on), and pursuing sexual holiness. These devotions together can develop into a couple-centered spirituality that begins to replace the church-centered relationship with God that the New Testament actually prescribes.
Indeed, I don't know a single godly couple who would tell you otherwise. We need to feast on this truth regularly, or we will be tempted to draw strength from other, lesser sources, like your own relationship. First, they do the negative work of preventing the greatest danger in any “Christian” dating relationship—no, not sexual sin, but the human tendency to make an idol out of the beloved.
Usually this idolatry justifies sexual sin and so many other relational pathologies.
A heart that doesn't submit to listening to the law will be hardened against any call to repentance—that’s the death-knell of any godly relationship. Unless regularly reminded of the grace of Christ, the heart will begin to sink into sin, go into hiding, and find its deepest affirmation in things other than Christ—like an idolatrous focus on your relationship, for instance. ) into an idol, you want them weekly pouring out their hearts in praise to their true Redeemer and Savior.
Third, the Word of God truly preached brings us by the power of the Spirit into the presence of Christ. You also want your significant other to have communion with the body of Christ outside of your own relationship. Did you note the developing trend in the four points above?
Finally, we need to hear an outside word that we can't quickly rationalize, twist, distort, or ignore. If your relationship becomes the center of their faith, the main and only encouragement they have in Christ, something has gone wrong. All four stand on their own as solid reasons to be committed to gathering (and being a member of) a local body.
Who is there to support and encourage when you're having a bad day, or when your relationship needs a check because it's gone off the rails into sin? Even the best married couples need other, godly voices speaking wisdom, conviction, comfort, and healing grace into their lives. Whether you're a Baptist, Anglican, or Presbyterian, you want to be regularly reminded that Christ alone is the source of spiritual life—he died, rose again, and our union with him is the only true food for your soul. Yet all four play an important function with respect to your relationship to each other.