I enjoyed that episode very much -- one of the few in Season 7 that I like -- but read it somewhat differently. I don't think Ro left because she hated Cardassians; I think she left because she empathized with the plight of the Maquis. They're living the life she grew up living: displaced from their homes, fighting against a powerful and cruel enemy that wants to take all that is theirs.
Given her history, to say nothing of her more recent troubles, Ro should never have been the one to infiltrate the Maquis. She was conflicted from the very start, and I find it to be a sad ending that the only time we saw her forming meaningful relationships and finding her sense of "home" was among struggling people engaged in a hopeless quest and living lives blanketed by uncertainty, fear, and anger.
It's a tragic ending, I think, that was punctuated by Ro's regret over disappointing Captain Picard -- the one person that she seemed to respect and admire in Starfleet, and who offered her a faith that she ultimately felt forced to betray.
And when he heard the news of Ro's decision, I don't think Picard was time-shifting... I think he was contemplating the situation, and probably was feeling a measure of deep disappointment in himself for having allowed Starfleet to put Ro in that position to begin with. He let his feelings of pride in her redemption, and his determination to give her every chance, cloud his better judgement (which he should have expressed to Nechayev). I think he feels like he failed Ro rather than vice versa.
What do you say in such a moment? What can you say? You just feel...
As an aside, it would be interesting to see what Picard and Ro would say to each other during their next meeting -- assuming Ro survived long enough to meet him again.