Arrey..why r u comparing her mistake with her past..U don't have to go back, CVS showed it that in same episode where sonakshi went wrong...
If u have noticed she is giving lecture to saurabh about that he doubted ronita only on basis of assumptions and repeating same mistakes as what dev did to her..
But when dev came bose house with soha, she also started bashing him only on basis of assumptions that because of Dev, soha got hurt.
So that's show sonakshi is also Wrong if she thinks that only dev doubted her in past only on basis of assumptions then sonakshi also done same with dev in their fail marriage.
Very beautifully parallel shown by CVS There.