The fact that anita has returned is just the start the icing on the cake will be the letter revelation now that gopi knows how to read this will be the main reason she leaves. she had told urmilla that she did not want to marry aham because he was in love with someone else but instead they lied to her.
Ahem will find gopi gone, hopefully when he remembers what happened on holi, he will fine the letter on the bed n will have flashback the day he read the letter n found out that gopi was unpar n how he slapped her. he will remember what gopi said to him. if gopi could not read this letter who read it to her, then remembering how rashi tricked sonal into canceling her wedding. just a prediction what do you think