I didn't get your tone at all. To be honest, it's more likely, that I'm unfairly projecting because I've had 7 people reply to my post with essentially the same thing: he lied to Alicia and he slept with Ramona. And all I've done is be the only person in the thread (apart from OP) to say that I do feel sorry for Peter and these are the reasons why. It's a little tiring at this point (nothing against you here!).
YES! This is exactly what I think is happening now. Alicia couldn't convince him that she wasn't sleeping around, Peter couldn't convince her that he wasn't sleeping around. So eventually, both of them stopped fighting the charges. And I think they did that because they'd both moved on from the relationship at those points. Why fight someone on something if you no longer care about their opinion?
We're gonna have to disagree on the 'Peter pursued a long-time family friend' thing. To me, it also seemed like he was helping out a family friend and it turned into something more. I don't think anyone on this show does anything for just one reason, especially Peter. Although, if that did happen, it's no more gross than Will Gardner giving a job to Alicia Florrick, a woman that he'd apparently been in love with for over 20 years.
I also don't think Peter was 'succumbing to Alicia's anger'. I think he was just not willing to engage with her or fight with her. To me, it seemed like a refusal. I noticed that the entire time he was with Ramona, he didn't fight back with Alicia. It was mostly Alicia yelling at him, and him not engaging. It seemed to me like he just didn't care about Alicia's thoughts on anything personal. And I just don't think Alicia would've actually stopped and listened if Peter had told the truth. Almost the entirety of S6 has been about Alicia and Peter NOT listening to each other and listening to other people instead. Alicia and Peter's marriage is one of the most fascinating aspects of this show for me.
I really love how morally gray Alicia has become. I love that she isn't perfect or saintlike. I know people get pissy about it but I don't think this show has ever hidden then fact that she is a perfect superwoman. I think a lot of her hypocrisy, moral and ethical issues have been there since S1, it's just a lot harder to overlook them or explain them away now.