I liked this chapter in some aspects, but the tropes slightly took me out of it. I can't even begin to count the number of romance stories I've read where a rainstorm triggers them sheltering in one character's house, which is followed by bathing drama. Then the author combined in the ever-prevalent "character faints in bathtub" trope, which has always been a strange one (clearly the Japanese all bathe in temperatures at the edge of human endurance).
As for the ongoing debate/discussion around romantic/sexual identification terminology, it's very complicated, obviously. Attempts to simplify it inevitably remove complexity and exclude at least someone somewhere. (Which I'm about to do, so I appreciate the irony.)
An analogy I like to use is to think about sexual attraction as a vector. Vectors are mathematical line functions that consist of a magnitude and a direction. The directional component of a vector of sexual attraction is the person's sexual orientation. Strictly speaking, this is what the 'LGB' terms were originally used to be a catch-all to represent. The magnitude component of a vector of sexual attraction is the level of sexual interest you have towards somebody. This is where terms like asexual come into play. There are probably a very broad range of sexual interest levels (not just 'sexual' and 'asexual'), but there isn't great terminology in this area to describe them. Some people may use terms like hypersexual or celibate, but those terms are intended to answer a different question that is less about initial sexual attraction and more about ongoing sexual activity.
Pansexual and demi-sexual are terms answering a different question ('why are you attracted to the people who you are attracted to?') that is partially related. Lastly, romantic attraction/love are different concepts for the most part.
All of this is compounded in complexity by how hard it is to fully understand and know even oneself. This is partly what manga like this one are showing. Everyone assumes they are one thing (or don't even think about it) until they grow by either physical age or by meeting more people and being exposed to new ideas.