well 'liked' him would make no sense because
1) She herself distanced herself with him
2) She seems to be getting along too well with one of the main guys who harassed him
she was shown in multiple flashbacks to have been effectively spineless, and because the ML was being ostracized by all his peers, if she stuck by his side she would be mocked/bullied by association.
She feared that most of all, and so she cowed before the bullies, and looked the other way or participated in the collective abuse toward the ML because otherwise she'd also be targeted.
For his part, the ML understood this and that's why he still doesn't hold a grudge against her to this day.
But even her behavior alongside the asshole who went to their middle school is her just being meek and cowing before him/going along with him out of fear of persecution, than it is her outright endorsing his behavior toward the ML (and the FL who was initially on that committee for the festival where they all meet/re-meet).
So I think she very much has always liked the ML. She just feared being bullied more, and made the decision that saw him ultimately leave her behind to her ongoing misery and suffering.
I forgot but that’s his ex friend who didn’t support him right?
Flex on them by holding both girls now
Yep, she's the friend he'd made back in childhood, who was close by him and gave him that "hero" concept that he aspired toward (because he was so different from everyone around him, even then) - until middle school, when his differences made him a target for mockery/bullying, and she abandoned him because she was too afraid of also being targeted/ostracized by the rest of their peers.
And yes, she apparently regrets it to this day, but remains unable to actually grow a spine, it would seem - and he holds no grudge, but has his twin GFs now, to boot, so.