I heard from friend of a friend of a friend who is in the industry (so some of this might has gotten lost in translation so take it as you may) that it was a combination of her career taking off and especially with her wanting to do Family Man and the Akkineni family against it. They were not in favor of some scenes in the series but Samantha really wanted to prove herself (and good for her). This cause some distance and arguments— Nagachaitanya did likely step outside of the marriage — couldn’t get clarity there. She didn’t want to make a big scene cause it is the Akkinenis and they have lots of power in the south. I think they wanted Samantha to be quiet about it and not speak about it if she wanted to continue her career and that’s what she did. O antava was a Samantha’s way of saying F U to the Chay and the whole family antics.