I think the biggest problem this series had was that the author was certain they'd win, so they didn't even try to consolidate the story into the confines they were given, it's either that, or they ran out of content right before the rival arc, and decided to fluff out the remaining few chapters. I'm not upset it ended, though I am sort of frustrated that it was wrapped up so poorly, even if it was a bit of a less than stellar entry into an oversaturated genre.
I won't go into the nitty gritty, but I just didn't enjoy the leads, at least, not with each other. Separately, sure, they're fine characters, but their personalities contrast a bit too much, even if there's the whole "opposites attract" ideology in romcoms. We're given a struggle between the softer male lead's perception that romance between them is impossible, and the more aggressive female lead's pursuit, and this isn't necessarily a bad trope, but it's hard to not understand where the male lead comes from given her anger and the actions it leads her to take, her overall pushiness that goes a bit too far a bit too often, her immensely gifted lifestyle that would make anyone feel inferior as a result, and the fact that his past experience with her was being bullied. It also doesn't help that she has everyone essentially kissing up to her constantly, including the MC's sister (whose whole persona apparently only exists out of respect towards the FL, which puts a bit of a damper on her somewhat fun character), and it really feels like everyone is just living in the FL's world, with nobody expressly on the side of the ML to at least let his opinions feel validated at times when the FL isn't telling him what they're going to do or how he feels or whatever else. It was a short series, so sure, letting the ML have a friend or something would have just given the author more work on a tight schedule, but it definitely felt a bit wrong that in every single interaction, he was just dragged along and essentially forced to deal with it, with him never able to express his feelings to any extent while we got basically every single thought, feeling, and opinion of the FL. They could've at least given him and his sister a moment to be real, but instead, they never get interactions without the FL around, and we see more screen time of her and the sister than the ML and his own sibling. And the rival? Basically just a copy-paste of the new modern rival trope, black hair and sense of superiority included, who exists just to degrade the lead they're "facing off against", so I'm not even going to bother with him.
This series is basically everything I've come to dislike about modern day romcoms, rolled up into an improperly-sized package. It has a romance that's more forced than anything else, an uneven power dynamic supported by an FL that doesn't want to change the heavily skewed nature of everything, the most standard and unenjoyable rival ever, and a ML that exists essentially just to be put down by everyone else for being "lame" or "boring", despite constantly showing how kind and considerate he is.