Well, he saw an opportunity and took full advantage of it, eh? Despite being caught by a girl who urged him to continue, he certainly obliged her.
Him saying he cared only for the uniform and not so much her on page 12 though...I guess his response was pretty predictable. Expecting something from an insensitive protagonist like him probably isn't the best way to go about things, so her pretty much just pushing him down and having sex with him was probably the best course of action.
Great ending though. I'm sure one day he'll discover that it's not so much the uniform, but the girl wearing the uniform that matters more.