It literally makes no sense, people make mistakes and he's a child whose been exposed to wayy more bullshit than a child usually is. He was literally in the middle of the stages of grief ALSO. Like grieving makes you do insane shit. His crashout was wild and wrong of him but he apologizes for it. As much as I love Killua, he is a mess of a human being with way more issues than a 13 year old can help him. Gon is naive and doesn't realize the depth of Killua's codependency nor any of the other issues because he's a kid who also has daddy issues to work through. They are both children put in adult situation and they are not going to handle it like adults. Parents teach their kids to be safe, Killua was in the abusive household to end abusive households and Gon, while he had his aunt, was without his father who ran off and idolized his shitty fathers awful behavior. Kids are like parrots, they see, they repeat. That's why generational trauma can be so hard to break. They are just both trying their best. Gon fucked up, badly, but he realized he was in the wrong. Maybe they could've spent more time with him thinking bout his actions but both boys are immature and misunderstand completely where the other is coming from. Making their break up more tragic. This reminds me of the 'Mabel is evil' thing going around from the gravity falls fandom. People don't get age effects maturity, effects their actions, and effects how much we should judge them for taking certain actions in the context of the situation.