I actually think Ross and Rachel's official breakup was one of the most delicately and appropriately handled arcs of the series. Don't get me wrong, I LOATHED the drama and issues that led up to it. But the actual breakup episode was fantastically done, IMO. (Although, as Monica said -- albeit selfishly -- it IS a little far-fetched and unbelievable that neither one of them would have stopped for a minute and wondered aloud where the hell Monica was.)
I think Ross's most detestable behavior on this show was his reaction to Joey's burgeoning romantic feelings for Rachel. He does everything he can to act like a total martyr about it and make Joey feel like shit, when the guy ALREADY feels like hell over his feelings. It's not like Joey was even planning on pursuing anything with Rachel; his agony was stemming from the knowledge that he never could, given the situation. And does Ross do even one thing, or even offer one consoling word, to make Joey feel better about it, at least before Monica finally talks some sense into him? Of course not. (And even after Monica talks to Ross, he is cordial to Joey at best. There is no true empathy or understanding shown, it's more like "Well, I mean, I don't totally hate your guts over this, if that's what your worried about.")
And let's recap: Throughout Rachel's pregnancy, Ross dates Mona fairly seriously and flirts shamelessly with Katie from the baby apparel store. When Ross is trying to resolve his issues with Rachel going on a date with Cash (Joey's costar), he actually says to Joey that he doesn't want a relationship with Rachel and that he "can't force himself to fall in love with her again." He shows no indication of wanting Rachel for himself, and yet when Joey needs his support, he acts like he owns the woman. Detestable.
Now, do I see how it could potentially be awkward for Ross? Sure. But his degree of self-perceived ownership of Rachel and any type of feelings toward Rachel is ridiculous, IMO. And it continues all throughout the series.
