I first discovered this genre about 15 years ago when a straight, Mormon friend of mine became entranced with it.
His enthusiasm rather baffled me until he clued me in to some of the cultural context. He's a pretty self-aware guy, and he realizes that he romanticizes early Mormon pioneer history. He consciously rejects sexism, homophobia and other unattractive cultural phenomena of the LDS Church, but he still romanticizes a certain pioneer aesthetic that he glimpses in Amish romances that he reads as fantasy.
I live deep in Amish country, so I have a different take, more grounded in reality. Most of my Amish neighbors are lovely people, always friendly, often willing to lend a helping hand to somebody in need. (Though help is more likely to happen with fellow Amish than with other neighbors. Human nature and all.)
I'm also aware of the less positive side, of an insularity that often puts Amish women and girls at risk of sexual abuse within their communities. I'm aware that about 40% of children born to Amish families choose not to be baptized in the church, which leads to stigmatization and even shunning.
This puts members of the 40% (many of whom identify as LGBTQ and would not be able to live openly in the Amish world) at significant disadvantage in life, given that Amish children do not receive effective general education like other American children.
An 18-year-old who decides not to join the Amish church not only lacks a high school diploma, but often lacks easy familiarity with English.
Needless to say, their employment prospects are dim, given that their meaningful skill sets are mostly based in 19th-century agricultural and crafting technology. Some former Amish find work with those skills, but most are unable to, and end up living on the margins, impoverished.
Women end up the most marginalized.
I don't have a problem with Amish romances as fantasy, but I do wish more people knew the reality.