Riding in a small group

I would think that, yes, that's generally the point of a group ride. But if the riders have hugely different abilities, then maybe slightly different groups might be in order.

Every group is different and unless those ground rules are set before hand, then there's no reason to believe there's anything wrong with the way he's doing it.

If he's a much stronger rider than the rest of the group, it is probably very difficult to stay together.  If he's pulling the entire way, then good for him.  If he's just riding away from the group, he probably needs to invite some faster riders. 

This.  Group rides are a great lesson in communication skills.  If expectations are communicated beforehand - or even after, if you're left scratching your head over something - then there's little expectation that the group would stay together as a "group" particularly if you do have folks of different abilities there.

The group I ride with (it's been awhile) is small--usually 6-7 is max--and there's a guy who is very strong, very experience and VERY fast who attacks and takes off every time after the first, oh say, 20 min.  There are one or two who can go with him, at least for awhile, but I can't.  There have been a couple of times he's waited for the others, but most often he doesn't.  In other words, it's not a "no drop" group.  A part of me feels really crummy being dropped--fast--every time.  Another rider told me not to judge myself compared to that guy, but to ride as best I can.  On the other hand I think it does make me work harder and ride faster.

I live in a small, rather isolated city/town, so there aren't any other groups like no-drop groups I can ride with.  Like I said, a part of me knows it's good for me.

From my experience, if you're riding with a group of roadies on a no-drop ride, the pack stays close together and drafting becomes important.  But if you're riding with triathletes, the gap opens up and becomes more of an individual ride with unspecified stops (usually at turns/lights) to regroup for the next stretch of road - we also have a SAG rider in the back to help guide the really slow folks.  I prefer the latter since it allows me to ride at my own pace, without having to worry about getting lost.