Nope. But the way he went about it was wrong. He could have shown a bit more sensetivity

Absolutely! I think he was trying to make Hermione jealous,
and he didn`t care much about Lavender :S

But we've already talked about this.

Not really.

Oh, really now, fuck me with this mature-immature thing. Ron wasn't immature because immature because he dated Lavender, he was a coward. And not because of dating Lavender, but because he had no guts to walk up to Hermione and ask her out - he rather hooked up Lavender (which was really not such a whole romantic and pretty story, as Lavender was the one stalking after Ron and he -again- only picked her because she was offering herself and no actual action was required from Ron's part). AND Ron decided to get together with somebody (who turned out to be Lavender because of the upper mentioned) only to prove Ginny wrong who claimed he was a frigid loser. That's not necessarily immature, guys are like that.

Extremely

very

I don't see how it was immature. He went about it the wrong way and he should have been a man and just asked Hermione out but he didn't.