Why would purva change her plan??

I keep on reading about how Phaiba is going to cause friction between purva and smriti by bringing smriti and mihir together but why would this make purva mad? 😕doesnt she want smriti and mihir to be together?? 😕😕😕😕 since smriti came back she has tried in many occasions to bring them two together so why change now. and as for smriti i doubt she will do anything with mihir because she doesnt seem like the type of person who puts her happiness first before her sisters...after all the CVS will never let her experience HAPPINESS 😆😆