
Can someone explain to me why he had to apologize? I don’t understand how showering at the gym is a bad thing.Thank you.

It wasn't about Haroumi showering at the gym - rather it was him taking Senri to the gym and having the the child shower there.
Its okay for a child to go to a gym, if they are old enough - which I doubt Senri is at the moment. And having a toddler shower at a gym where... imagine the hygiene issues for a small child. No matter how clean it (gym showers) may claim to be, a very young child is very sensitive.
As the story progresses and if they get into a relationship, is the seme faithful? I’m kinda worried since I’ve seen him fuck quite a bit.
Yep he's really serious about their relationship (▰˘◡˘▰)
He is very faithful.
He’s very faithful it’s just that he needs blood to live and to feed him so I don’t think it has the same meaning behind it anyways