The characters are incredibly emotionally mature and well thought out. At one point they do character bios on blackboards, and 1/2 the information is plot relevant, 1/2 is just natural explorations of the character to give them more depth.
If it feels like the characters are too emotionally mature to the point of being unrealistic, then you should do something about that, whether it be taking some notes on how to be better, or surrounding yourself with emotionally mature people to make it a reality.
To me the drama feels lifelike in the sense that to each of the characters, it means the world to them, because at this time high school is their world, their friends and relationships are their world, so why wouldn’t they be wholeheartedly invested in it? Why would they not pour their heart out into every apology?
Checkov’s guns going off left and right in the unposted chapters (110-120) ish, so I highly recommend reading it off another website. Also the boys have a real sense of style so take notes.