what is forever? ( angst)

"Samu, what does forever mean?"

"Huh? it's just something that lasts I guess, why?"

"then you'll be my brother forever?"

"Yeah, that's how it works Tsumu, why?"

"are relationships something that are forever?"

Kiyoomi has been cheating on Atsumu with Osamu, and Atsumu finds out. he starts to question everything to see if he can get them to admit what they've done, but it doesn't seem to be working very well.