Had this show started when FL was already in university it would have a bit of a higher rating on my part, I found from that point onwards it was more entertaining, not great by any means, but better. From the beginning up to that point I almost quit several times solely on the fact that the FL was EXTREMELY annoying.
I'm not familiar with the actors in this show nor I generally care who is in what. There are actors I like, but I won't watch something only based on that. I say this because I don't know if the acting of Zhao Lu Si is her or it's the director and direction that pushed her to do that (and in that case not sure why they would be happy with that result). It was extremely annoying how she was acting as a 17 year old like she was 7. She was shown as more mature at age 14 in her way of speaking and mannerisms (although physically that actress was clearly younger so it was also very jarring).
I think at this point after two cdramas watched being set in high school I should avoid cdramas set in high school. It feels at times like I'm watching a video on morality and good manners directed at high schoolers, like the civil education videos I had to watch when I was around 12-14 years old. It's also so forced how they try at some point or another say some grandiose moral quote like they're talking to me directly instead of the character.
Also, for the love of all things dear, how was she so dumb and childish when technically she had good grades in school? It makes no sense at all.
They want to show later in university that she's more of a grown up but there are so many things in her way of doing and especially her voice that she still seems so childish. On the other hand ML changes completely of character once he's starting to be interested in her, he's all of a sudden super cocky and flirty, it was very out of character. From that point onwards it's like they're trying to keep reminding me that she's a girly girl and he's a boyish boy.... MEH.
I still don't understand fully how or when Jiaxu started having feelings for her, it's kind of sudden.
I didn't care they didn't show much of the drama involving his father because I had zero interest really, it seemed kind of typical and like it was not going to add much to the story other than some cliché trauma, but I didn't understand either why introducing that daughter of the family affected, she was very annoying and contributed nothing to the story either. I'm guessing she was only there so FL could show her more "mature" side but it's very weak.

There are some cute moments, but overall I was not so sure of why they liked each other, I'm not even sure why she liked him in the beginning to be honest, just because he was handsome and nice to her? not sure, I'm not shown at any point in the first or second half that they share anything when it comes to personality or likes or hobbies, they barely share even that many special moments. It's also very weird because he goes from calling her "sister" to 5 minutes later being interested in her, I couldn't shake that feeling of uneasiness, and it brings me to the fact that the sister thing was way overdone. It would have been so much better had he just been the brother's friend and kept that relationship of friend than making it so far as to his feeling of her as a sister, I felt that put a big barrier on there that I couldn't see a way of it being broken and so I was not surprised when it was just done suddenly and didn't work for me at all. It's also quite annoying when she's already in uni and she keeps saying he's old and they keep mentioning the 5 year gap, what is not a big one by any means.

As it happens in the other cdrama I watched recently (When I Fly Towards You), everything is shown in perfect stages, high school is the time for little crushes but ultimately focusing solely in studies, university ok for relationships, and as soon as you finish uni then get a great job straight away and save to quickly buy a house and start a family. It's very unrealistic, and after this being the second one with the same idea I'm starting to think that they're trying to precisely sell me an idea here more than a story. It was equally unrealistic his career, how he's able to achieve all that at his age, no problems in anything, same with her really, nothing of much importance. It's also the fact they feel the need to include in the story the whole process instead of only one part of it, it gives it even more that feeling of someone showing "how it's done" to me so I take it as an example.
Characters are also generally always kept superficially and secondary ones are pretty non existant.
I found the brother quite annoying at times as well, why was he ten times more patriarchal than the father? I know maybe he just has the older brother complex but seems so weird when it doesn't seem they have that dynamic in the family. Her parents were all right but I didn't really understand why they let the son be that way with her or take more charge of her than them, it was weird some times.

The ending is... well... the cherry on top I suppose. It was quite shocking she would be proposed on the same day of her graduation, like chill man!! Another cdrama that pushes the marry young idea, but I mean, considering they got everything else at unrealistic young ages no wonder by 22-23 they're bored of their lives and they need to marry or something ? (I know he's older but still applies, it's not like he had to do it like he has an expiration date and as far as we know he was not being pushed to do it by anyone either).