I read up to chapter 39 and the story thus far is ok. The story doesn't get side tracked and the ML and FL are cute to read.
From the first half of the story it is pretty clear the FL is a marysue in the original sense. She is beautiful, rich, kind, well mannered, she is the embodiment of perfection, if you asked me what her personality flaw is in the story I honestly couldn't give you one. She makes the one mistake of loving a jerk and that is it, not much of a flaw honestly.The story keeps mentioning that she has flaws, or had a bad relationship with her family, but we never get to experience any of those things. Characters are supposed to be written with flaws so that they can grow throughout the story, however the FL is already perfect and has nothing to work on and no growth to make. She has everything except love, but her personality is so perfect that she found that faster than you could make a sandwich for lunch.
The ML suffers from the same issue many shoujo ML's suffer from, a lack of personality outside of the FL. His whole entire world is the FL, does he have hobbies, is he well educated, what exactly does he do in the dukedom...does he have any type of work? It is hinted that he would like to make friends, so it would be nice to see him grow into the more confident person he wishes to be.
So far all of the supporting characters are standard wing men with nothing more to their personalities outside of being wing men. The villains are written the same way, they do have motives, but they don't have any personality traits outside of being greedy, ambitious, and selfish. The female antagonist I will say gets a bit more depth into her inferiority complex which I believe is a good step for the story to go in when trying to humanize a villain and add a bit of depth to them.
Overall I would recommend this as a light and fluffy read. If you are looking for something deep, exciting and unique then this is not the book for you. I would recommend this for people who enjoy lighthearted feel good stories that don't evoke any stress because you know everything will work out. Its a very safe story about two kind people falling in love.