At first I was pissed at the commentators for calling MC edgelord (from the first 3-4 chapters). Now at Chapter 19.........He truly is edgelord. The girl didn't abandon him, she tried to comfort him the best way possible. She even got physically assaulted once. So realistically what could she do more?
If you are not willing to defend yourself (like he did once), don't expect others to defend you.
As someone pointed out here, author decided to change direction from first chapters to Frederick N. aka as if he was gloomy from the start and situation simply worsened.
In any case this manga seems to be a wet dream of a highschooler aka mangaka. So called 8th grader syndrome that managed to get LN and manga though i doubt it will get anime.
Read the comments about WN, 2.6 on novelupdates, Some people are positive whilst others are not so positive. As they stated WN is canceled due to authors decision to work only on LN. LN is quite different to WN (sadly i don't know how different).
As stated about WN, it's slow, edgy contains a lot of brutal stuff (senseless murder, rape and etc.) <--- I suspect this will be cut out from LN since it's shounen. MC doesn't progress much, though his "alter egos" have different personalities (I guess Oscar goes to MC). Through the manga you can see our MC and his first alter ego are 2 completely different people, so he can act positively he simply chooses not to.