Here is the bottom line...Ahem may have said ILU to Anita, but it was not real love. They both fitted each others version of what they wanted in a partner. Ahem was only thinking about his lifestyle and Anita fit in it perfectly.
Now Ahem is 110% in love with Gopi and he knows it. He is trying to make her comfortable around him...because she still is distant, due to him of course...and then he will confess.
Anita coming back only means he is going to get closure for his past guilt. He can now move on and know he may have hurt Anita, but she is happy and she is getting married. That was her Mehendi. She is the one getting married.
So don't worry. Anita is not there to steal Ahem away from Gopi...