@luckpack
Well the good news is that there's no power imbalance with Emiel and Estielle. He's not raising her, and she's his employer, so the power balance is tilted in the opposite direction. Also, there's no 'grooming' going on for the future. Any romance will come later, after she's reached adulthood. And even then I don't think it's an immediate thing, just a courtship. This is a Christian mango, after all, I'm sure.
And while I'm not a fan of the Quran permissions, I say it because it does seem like you're judging with a particular culture's eye. For example in the Muslim and Asian world, consanguineous marriages are commonplace. From Morocco east to Pakistan and India etc, all of those nations have high rates of blood-related marriages (often, first cousins). The rates of blood-related marriages goes from like, 25% to more than 67% in places such as Alexandria, Egypt. I don't know about age differences in all those relationships, but it's quite common throughout history and the modern world for the man to be older than the woman. In America, the rate of blood-related marriages is less than 1%, so naturally we're going to see it very differently, and much of Europe is probably similar.
I myself, now that I'm single again, would absolutely have no interest in dating a woman my own age. I want a family, and I'm now 39, and there's just not enough time to start to date someone and have a child with someone my own age. So naturally, I will look to pursue a relationship with younger woman of child-bearing age. In that regard, my preferred age range is 25 to 29, but I would absolutely go lower (and a bit higher) if it was the right person. As far as what society thinks? Well, it can fuck right off, because it's a personal choice between consenting adults and society just doesn't get a vote.
Now, I think I'd be more compatible with a woman who is around the age of 25 rather than 18, but if a beautiful 18-year-old was interested in me and wanted to pursue a long-term relationship with me, of course I would consider it. Obviously that's unlikely to happen, since, most young women aren't interested in guys that much older - but obviously, some are.
Also, "power imbalances" aren't the end-all be-all of establishing whether a relationship is consensual or not. I'd say a beautiful 20-year-old college student has a lot more power in a relationship with an average 35-year-old than a 35-year-old career woman does. The older woman has way more at stake, far less time to make decisions (bio clock goes tick, tick, tick), and has far fewer options if that relationship doesn't work out. The 20-year-old can say "it's over, we're done" and have another guy the next day, but the older woman can't do that.