The thing is, Peter's put it all behind him and has shown remorse and since then, he hasn't ever shown any indication that he'd falter again. Even when the beautiful blonde pouty lady turned up (I forget her name- the pregnant pop tart one) he was always well behaved. Alicia on the other hand, looks like she'll jump into Will's arms at any opportunity and has been unfaithful since too.
Anyway, I too, think they're all fab characters. All of them with such depth. The only one I'm not so keen on is Micheal J Fox's character who is extremely irritating and also this new Irish cocky guy who's too far up his own rear end. I mean, which idiot goes and steals all the furniture from someone else's office and gets away wih it. Jerk.
As you can see, I'm far too invested in his drama. 
I'm ashamed to say that when I watched 'THE' episode I had to get out of bed again to watch the next episode because I couldn't sleep thinking about them all. And because they didn't show the conversation between Cary and Diane that she alluded to when firing the insensitive client I ...um... erm.... I made it up in my head and imagined it out so I would to miss it.