A big BUT there. It may sound realistic, but calling it a novel or playing in a different world as a game is just stupidity. The lvl of airheadiness she has is way too much. If you are into reading mystery horror novels try Lord of the Mysteries (LOTM). A girl like this wouldn't ever, ever survive in that world (more like die many times over). It's so dangerous that every mystery has a consequence and gaining more power is at the cost of losing mental sanity. Also, it's gets so good that even though there are 1000+ chps, it's worth reading, way better than this cliche thing. Horror background somewhat similar to dark beings and the like.
Also, MC feels way too naive, minus the transmigration and she's no different from the OG body. Applying novel knowledge in a different world isn't always helpful. Even though her fantasies were fulfilled, she still lacks common sense. Moreover, no one bothered to correct her innumerable misunderstandings, more like she didn't bother to. It was so bad that in chp. 9 I wanted Lucas to stab MC from behind as a plot twist just to turn her 'romance fantasy' into a 'revenge' one. Her rose-tinted glasses are so thick that she's just blind.
Sure, wanting to live peacefully as a rich family is great and all, but she is over optimistic, stubborn to change and brushes aside everything. Just because she acts as the FL doesn't mean the world completely revolves around her. Also, the impeccable timing of horror happening behind her back is just blind plothole, that's why she still even upto the recent chps. doesn't know what the actual nature of those roses are or even what rules exist for every servant.
A different twist would be welcomed like another transmigrator killing this FL and just erasing the happy ending thing. The laughable part is what she considers as her fiance is one who never cared about her life and death and only treated her as a hamster, he changes for the better but FL doesn't.
Well yeah she is a big airhead that's right, still she hasn't been here a long time, she just came in and the people have always been this way, she is still in her excited happy phase butterflies in the stomach from being reborn in a new world, and as she said in this latest chapter her real life is so horrible she would rather not go back to it, she likes it here and Jeryl has been hiding the truth from her, everyone has, she's just someone with a different perspective. For her she went from a hard world to a novel world, one of dreams that make it into reality, she's so happy and is discovering this world, if anything she's pretty fast at it compared to other characters who take it top seriously, taking things so seriously is bad for your health, I like her way of thinking, since you're stuck here either way you accept it and go with the flow, living well while also exploring and discovering new things, she isn't such an airhead as we thought, she took pictures, spoke to people to gain knowledge and went out of her way to buy guns to protect herself and her brother, though she still doesn't know everything that is happening she is still taking her precautions, she also shot the Gardner when he showed his true nature, more MC's are scared to actually shoot, she wasn't, she did it quickly and efficiently, she is great, and she has an optimism about her that is amazing, im glad she doesn't lose hope and decides to take things as they come, to even go and face it ahead, she's strong, a warrior, she doesn't simply wait for things to happen, she doesn't hide, she goes and faces it, that is the attitude the great ones have, taking things so seriously to the point you get sick and start overthinking everything, you can already see it in Jeryl, and what does it do? It Paralyzes him. While she is free to roam around, simply thanks to her confidence in her knowledge and abilities, if that's what makes her strong, why are so many so Butt hurt about it, what someone working hard and being happy at the same time because they want to appreciate the second life they were given is seen as weird?
Fine then, let us be weird, I like her, and I'm with her, also I'm not even into horror, I like anything that has an actual plot with interesting characters, and she is one we don't see often, she's new, intriguing and interesting, she also makes us happy, looking at her and reading her story makes me root for her and I'm invested, I want her to have her happy life, happy novel like fantasy romance life, I love her.

She's very very smart, I know people don't seem to notice it since she's not like the usual characters but isn't she right?
Getting reincarnated in middle ages Europe or wherever else as an aristocrat, she's obviously not a villain so it must be a main character with a tragic backstory, it's so obvious!!
The ML her fiancé is gorgeous so of course she'll think like that, you all would!!
No we all would if we were in her stand!
Her strategies are true to what usually happens in a novel and maybe she really is in one, we just don't know it, she's a great and logical main character!
She has a handsome, capable, caring, gentle and wealthy fiancé of course she'd be happy and want to love him, she's an aristocrat and she's pretty too, also either a Main Character or an extra with extra luck, like srsly, so far it has been pretty understandable, and of course she's positive and optimistic, she d*ed yet she reincarnated and in a world with such a lovely storyline from her pov, and objectively speaking she is living the life, no tough work to do or responsibilities, she can just enjoy her life and the rise, sure some things are weird but she's so happy now and is used to reading novels, she can get through it all, she's right to be this way, imagine you d*e yet you get another chance at life, not only that, you're rich, no responsibilities, you're beautiful, you have a gorgeous fiancé, you eat as you wish, the garden is gorgeous, I mean everything seems awesome, even now the only bad thing is that gardener, sure the ML hasn't been all that honest but which ML ever has haha?
If anything, I love this and im so glad she's so realistic, we would all be enthusiastic to discover this whole new world where we believe we have all of these privileges, isn't that so great??