@Alncst: I get where you're coming from, but you gotta remember that everything you described is exactly what he did in his first life. The whole point of his second life is not to repeat the same mistakes he made. He knows he's limited and that he's not always right, which is why he's ok with someone else taking the leadership role. That being said, the real leader still defers to his judgement since he's more knowledgeable, but he defers to her since her ambition and willpower is greater than his and helps drive him to be better.
@Jesotku: Respectfully disagree. A lot of progress has been made. MC went from being a self-absorbed loner to someone who values his team. The three girls are romantically involved, but it was thanks to the MC's actions. True, the MC is unable to let go of his old man thinking, but he's not the 1st MC to do this. He's also still only 12 years old, meaning a lot has happened, but not much time has passed (maybe about half a year approximately). It's gonna take quite a few years before he acclimatizes to being a young man again. I imagine there'll be a timeskip where all 4 of them are in their late teens (or in Redia's case mid 20's) before it happens. It's all in due time...