I agree with your analysis as far as Vinu is concerned. Sai should fight tooth and nail but should not keep him with P. That doesn't mean she should go back to Virat.
As far as SaiRat is concerned, there were one or two times where I felt Sai went over the board before they parted ways. Pre leap I don't know why I used to compare him with Samrat. Samrat choice of woman is bad but that guy knew P is behind V. But I never saw him becoming aggressive. In fact he shows a lot of restraint and maturity while speaking with her.
Once you become an adult, others behavior holds a very small percentage for your mistakes. Most blames lies with you. Including Satya as well. If this marriage deal brings hoard lot of issues in his life, he is himself to blame for jumping into it as he is an adult.
That's how Virat has been written nd he is flawed ND no one is perfect, even in iv Neil said all are human characters in this show, there's no right wrong or any Mr.perfect kind of hero ,