Wondering Shagun why?

While everyone is ranting on positivity shown by Shagun , but i wonder why shagun first of all changed her name to Shagun Arora to Ruhi Arora? Whats her motive and plus hiding from Ishita in the hotel and then hiding from Raman and the Bhallas? I still cant get it what is she trying and Ruhi's concern , something looks fishy?