Didn’t she confess once and get turned down? What happened to make him change his mind?
Why did her sister turn from misunderstood pretty girl into the rival character?
What about MC’s crush on the blonde dude who then later confessed to her? Nothing I noticed in any of the early chapters suggested that the MC started to like the senior, until they revealed that the sister and senior knew each other.
And why did they keep it a secret? Why not just be honest and say “oh yeah, we’re friends, but nothing to worry about because we’re just friends is all”.
When did the sister character start liking the senior and why did she stop liking her boyfriend? Was she really a loose person like that to just ditch someone else in favor of another for no reason?