
Although most romances are not always as extreme as Romeo & Juliet, the goal of most romances is in fact to overcome differences or misunderstandings or tensions (of personality, social class, age, etc.) in order for the couple to get and stay together. Sometimes the goal is to overcome religious disparities/pressures. Those pressures supply the plot device that keep the main characters struggling until they understand each other well enough to form a unit.
A perfectly respectable plot, in my view.
It does help, however, if the religious pressures are MORE than a McGuffin.

I should say first that Andrew Grey is a perfectly respectable writer, and I quite enjoy several of his books, including The Best Worst Honeymoon Ever. In the case of Love Means No Shame, however, he might have been better served leaving Amish country alone.
The difference is the difference between a McGuffin and an actual setting/culture/milieu that informs the characters.
The Amish connection in Love Means No Shame is . . . well, there isn't really one except for a mention of "rumspringa" and Eli's clothes. And his feelings of shame. But really, he could be a traveling circus performer who abandoned his family or a cosplay actor who absconded with someone's lunch money or a freshman who dropped out of a college and doesn't want to go home and tell his parents. I'm not sure why he needs to be Amish--other than that the story takes place in the country. Maybe because Amish-romances tend to be surprisingly popular (like Laura Ingalls Wilder tributes: all that wholesome living without pesky things like grasshoppers and disease and freezing to death).

The behaviors of different people within the community are also normal--the outspoken brother who will likely settle down one day and become a willing member of the community; the friend who experiments with "the world" but never honestly debates leaving; those who embrace the community's strictures; those who compromise with them (internally and externally); and those who leave.
The young men who leave both want to go (and feel it is necessary since they are in love) and don't want to go. Their uncertainty coupled with a realization that certain changes are inevitable is realistic and touching. Religion is not merely an obstacle or a thing to be overcome but an ongoing aspect of their lives; consequently, it informs the type of struggles they endure, especially in the second book when Isaac and David move to San Francisco and have trouble adjusting to "English" city life (their reactions are so thoughtfully and compassionately detailed, I suspect more research by the author).

I maintain elsewhere that writing well about religion is hard. It helps if one treats it like an active psychological and mental and even physical factor in the characters' lives--
As opposed to a McGuffin-like obstacle to be overcome.