>>149936173
Yeah, but a lot of that post-dates and was partially caused by Mike's depressive spiral(s). Prior to the first one he was more well-liked than any other character, got along great with Sandy, and Lucy & Paulo had already eased up on bullying him and were trying to be nicer thanks to Tess/Daisy/Zachary. The thing that pushed him into spiraling was mostly that Lucy acted like she was entitled to him. Though Lucy WAS absolutely awful, trying to guilt-trip and bully Mike, Paulo, or Augustus into accepting her. But it went beyond a normal emotional reaction to Lucy's awfulness, because Mike was irritable and unhappy even when Lucy was silent, absent, or irrelevant. That kind of dwelling is a depressive symptom.
And I would put the start of Mike's second depressive episode at the psychic premonition dream chapter. That was before the start of the school year and Lucy's return, Sue and Paulo had forgiven him, he was on good terms with everyone, and he was still in pretty regular contact with Sandy. So the only sources of stress that actually predate him starting to slip would be: the start of a new year, Sandy being less available, and lingering guilt about Lucy; but from all appearances Mike had already gotten over/solved the latter two, and he's never been shown to have much anxiety around school.
Overall, Mike's mental health just keeps collapsing further. And part of that is definitely him feeling stuck and like he can't rely on anyone, but that's a vicious cycle: Mike feels like everything sucks and he can't rely on anyone, even though people keep reaching out and he still has tons of friends, because he mono-focuses on the bad and keeps lashing out. Again, dwelling on the negative in a very depressive way.