Sona being the cause of Raima's accident is 100% the way any average ITv show would go, but if they go even slightly out of the box they could change the scenario completely.
So, we know that Rohit is a surgeon, but what is Raima's profession or what was she studying and working towards becoming while Rohit was in medical college?
What if Raima was secretly aspiring to become an actress? What if she was secretly going for auditions using a fake name and that's how she met Sonakshi? Knowing Rohit's upper-crust nature and family, she may have been embarrassed to tell Rohit. This would open up such an unknown facet of their relationship... Imagine Rohit realizing how little he actually knew his Raima. On the other hand Sona has never hidden any aspect of her life from him, she is proud of who she is and what she does and despite their different social status', Rohit has already come to understand and respect her for who she is.
Unfortunately, TRP dictates what route a story takes and somehow tears, misunderstandings and separations always seem to trump softer more nuanced writing.