This isn't a rom-com; this is a horror story! If I wasn't looking at this from a tropey lens, Nanase is actually freaky and has no concept of boundaries. She heard that Izumi has a fiancé and, just, shrugged it off?
Shiragiku did something, and she is still best girl to me right now. Really, her only flaw is that she cares for her family, which isn't a flaw at all. Compared with the others, at least. Akane, tragically arrogant and stupid to the point where Izumi is already out of her league. Kasuga, a tsundere without any redeeming qualities, the worst kind of tsundere to be. Nanase, for whom romance is measured using literally forced rom-com progression instead of actually meaningful relationship-building.
Izumi's perspective makes the most sense to me. Why would anyone accept a confession from a random transfer student? Especially if they are visibly uncomfortable when said transfer student is around?
Shiragiku all the way, everyone.