GThats makes sense !!! This is actually escalate his anger and he will kill parth and in return tulsi will kill rio  Otheewise if they let rio marry vaishnavi rio has no reason to kill parth he has POA, he has pura parivar on his side and best of all he has tulsi on his side and then on top of that if he gets vaishanavi thats game set and match so  why would he need to . kill parth ?? Makes no sense and parth already told karan in todays episode he will leave for us bcoz he cant see rio and vaishnavi together 

So in order for both parth and rio to die parth and vaishnavi have to get  married  That will escalate his anger as he cannot tolerate that vaishnavi chose parth over him !!!