I agree with the responses above. So whatever you want, but I'm guessing that you already know that, and want advice that gives you more direction.
Generally, if you have the whole world against a character and they are alone, with no support group, then the results will spiral down into a negative thing, and the character will become less human and more of a monster.
If you want a better ending, then by all means, include a buddy or a teacher, or even a group of friends, anything to help the person cope. Cause if you think about it, realistically speaking, without a support group, many of us would give up, turn into a monster, or simply choose another self destructive method.
However, this is your story, but if you want a mc that's alone and a good ending, you kinda have to make them a really strong character, almost to perfection, which is really really unrelatable in most cases. There are ways, probably, but it's gonna take a lot of work and without the positive interactions, it's hard to keep the MC from feeling unrelatable or spiraling down.