The biggest subgenre in Christian fiction is romance, and the definition of a romance novel is that it ends with the promise of a happy-ever-after. It doesn’t then go on to show that happy-ever-after.
Some women’s fiction novels deal with marriage.
But the focus in women’s fiction is more likely to be a marriage in trouble. As such, it shows the main character (usually the wife) and their marriage partner overcoming their issues. Although, if I think about it, isn’t that the definition of a healthy relationship: one where the people involved work together to overcome their issues?
There is also the problem of the nature of fiction: it’s about conflict.
As such, a healthy Christian marriage is never going to be the focus of a Christian novel (although it could be the backdrop). After all, fiction loves contrast, and what better contrast to relationship drama than a healthy Christian marriage? There are several Christian authors who do this well, including Catherine West and Elizabeth Musser.
Having said that, I do think their are some authors and series who do a great job of depicting healthy Christian marriage. The classic is Janette Oke, with both the Love Comes Softly and the Canadian West series (serieses?). Another example is Karen Kingsbury with the everlasting novels about the ever-growing Baxter family.
Neither series depict perfect marriages (although the Baxter novels come melodramatically close), but that’s good: there is no perfect marriage. And perhaps that’s something our romance novels should make clear. But that’s a topic for another day.