There's always room for character development. There'd be no point to a whole bunch of stories if character's didn't grow and change over the course of the narrative.
As far as this ML in particular, he's already been compared against the FL and shown to have stagnated at best compared to when they were younger. He went from being "the one whom she followed" everywhere to sitting inside all day doing nothing but playing video games all day.
His own mother berates him in the first two chapters, stating exactly that--and she has to browbeat him into actually helping out around the house in chapter 2, taking away his game console/controller to force him into doing chores. In contrast, the FL happened to be walking by, saw the ML's mother struggling outside in the garden, and stopped and helped of her own volition.
We see in chapter 1 that the ML & FL were comparable in their overall skills and accomplishments, with the ML even edging out for 'first place'. Then, he discovers video games in middle school, and becomes a self-professed shut-in who--again, per his own mother's words--lazes around all day in doing nothing. She wishes that he were more like the FL, as well, who is shown to be smart, athletic, and generally well-accomplished in high school.
The overall implication being established, is that the ML and the FL are archetypal opposites. She's cool, calm, collected, quiet, physically attractive, and accomplished. Thus, the ML is being portrayed as her opposite in most ways, changing right around the time middle school and the video games thing began.
He's very much being presented as having flaws that, ideally, he'll overcome as the series progresses. As of right now, the FL is being portrayed as this ideal that he currently does not measure up to, which informs part of their dynamic from his perspective on top of them being childhood friends and "pseudo-siblings". Yes, it's only 3 chapters still, but given we're likely to see them in school in the next 1-2 chapters, I'll not be surprised if he's also a middling student at best, given we're told he's always just playing games at home (even in this chapter--he was late because he was gaming all night. As opposed to the FL who was studying and doing homework. Again--another contrast, another showing that he doesn't measure up to her).
This isn't saying he's a bad character. But he's definitely being set up as requiring some sort of growth arc for his part of the story, because of the disparity between him and the FL.