Mullai is surprised by all of this

She's also very confused 

Then, she began thinking about all of this once again

Yes, she did shout at him every time on the phone. Yes, she did ask him why he came to her street? 

But that was all out of frustration that he hasn't talked to her or asked her to come home. She assumed his life was fine after she left. She felt like she didn't matter in his life. 

While Kathir was talking, Mullai's eyes filled with tears. How can she misunderstand her avagha. She can clearly tell that he was definitely not okay after she left. He was not sleeping or eating well. She felt guilty that she's the reason behind all of this. 

But while feeling guilty, she also feels awestruck at his confession. Even after shouting at him so much, he still wanted to surprise her on her birthday. Her GETHU husband didnt care about ego but simply wanted to surprise her and make her happy.

Mullai decides she needs to fix all of this right here, right now. 

As he finished talking, she took the gift cover and got up. She walked over to sit next to him. She sat down and give him the gift cover back.