Usually this idolatry justifies sexual sin and so many other relational pathologies.
Second, they do the positive work of setting your eyes on Christ and his completed work in your life.
Still, over the years I've come to see that there is key mark of a maturing relationship centered and continually centering itself on Christ: both of you are absolutely committed to each other's involvement in the local church. First, it convicts of sin and humbles us before Christ. If for no other reason than avoiding the danger of your significant other turning your own relationship (or you!
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.
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.