Thing is... and bear in mind I'm Aspie and didn't really have any male friends until I was 16 or so... but is it normal for teenage opposite-sex friends to touch that much? It seems surprisingly mature for the average teen friend-couple to have that level of physical affection without romantic involvement. I've never been huggy even with my female friends, but I can certainly see why Ron was jealous of Harry - she was constantly hugging him and hanging off his arm and holding his hand and resting her head on his neck and so on and so on. It doesn't ring natural to me. Being comfortable with someone doesn't equate to being that touchy-feely, you know? And they've been at it for a few films now, when the teenagers were at an age a lot of kids would still be "Ew, boy germs!".
I only had a few male friends in hs and I wouldn't (wasn't) touchy feely with them at all. However, I wasn't as close to them as Herm. is to Harry. A couple years after hs though, I had a very close male friend and we were constantly touching each other. A few people commented on it--which was irritating because we were both in serious relationships with other people (who understood). But, we spent about 75% of our time together (classes, computer lab, teamwork, etc) and the computer sciences is a stress filled degree and most the people are odd. So, if you find a great friend who can give a killer massage. . . awesome.