I'm sad that his friend turned out to be so....mean? Did he just honestly drug his childhood friend & threw him into the river because of some girl?! Wow, those years of friendship must have meant a lot to him... *cough*
@keks503 I'd actually forgotten about the friend since he doesn't get a lot of spotlight in later chapters, but his dialogue mentions he was a reincarnated person, so maybe he was originally from Earth and was an isekai fan; so when he got the near cheat level job of "sage", he probably figured "oh, I'm gonna be the OP MC that all the girls fall for just because I exist". People who think like that don't exactly react well when things don't go their way.