I have noticed this for awhile now, that Adam just doesn't seem to be as down with the other three. Dating back to the earliest days, he was different. They were religious, he was a partier. Later, he had to give up his smoking and drinking and guess what? The rest of them started doing it! I wouldn't image that other than the band they have all that much in common. Look, Bono, Edge, and Larry all have marriage or long term relationships and several children and pets. Adam has no one that I know of. Bono and Edge seem very tight, and Larry is close to them too, but not Adam so much. In the 60 minutes II interview, Adam was not even in the studio. When they announced the tour, Adam was the cardboard cutout. At the Slane aftershow party, Adam did not attend. At the aftershow for the recent Meteor awards, the other three arrived in a car together, but Adam came seperately.
I don't want to suggest that there may be trouble between them, because after all don't most of you work with someone you aren't mad at, just don't really care to have anything to do with in your personal life? Maybe he's just a different breed and they don't hit it off or get on as well. I don't think they'll ever get rid of him, or that he'll leave, despite recent nasty rumors. I think they have been together so long now they'd be too stubborn to break up the band, even if they only stay together for the sake of the band like some people do in sour marriages for the children. It could be he doesn't even play on all the studio tracks and only goes on the tours to be part of it and keep U2 together, but regardless, I don't think it's anything sinister and I don't believe they will ever break up. If they ever do stop, it will be as a band. U2 would never go on with a substitute member. They've never been that kind of guys. They've come too far down the road to start now.