I know this sounds odd, but this chapter is much more hard-hitting and emotional than the child-abuse and spousal-abuse chapter.
I think it's because we've spent so much time with Pochi and seen how much it means to him to find somewhere to belong and express himself, and that he's been so harassed for so long and put up with so much misandry that seeing that his only friends will probably reject him would naturally end up with sadness.
For FMC's backstory, we're just told it in a one-off by some nameless character and not shown the struggle or how it impacted her to any meaningful extent. That's where this chapter works and the others fail.