SPOILERS!!
I think I know some of the answers (or some good theories), like the reason that Ethan was killed was because Jude was jealous (the phantasma at the park alludes to Jude taking him to the woods and killing him there (I used that phantasma to figure out the Justice ending)) and a good theory for why the MC was killed was because they were looking around the morgue and Jude thought that MC had found his papers and got skittish about it. I also don't know why MC's death or body wasn't mentioned, I was really hoping that would show up, I also wanted justice (especially because Avery, the cloaked figure (described in a phantasma as "Evil Sneaky Guy") , mentioned that the MC was out there as in missing and not dead). I think the overall tiredness would be from the stress (and related disordered sleeping) getting to him, because another phantasma (I don't remember where it appears) mentions MC noticing marks on Jude's hands when they met (that's actually mentioned 2-3 times, the one I was initially referring to was the last time as it ties it to Ethan's death) which would mean he was holding that in for at least a month (for as long as MC and Jude were dating) and with how Ethan's grave was rushed this was probably some heat of the moment murder like with MC's.