He found out who Aiden is.

Standing by her means standing against Keller and Xander family. 

That means, putting his own family at risk. 

"Do you really like me that much, Aiden?" Anna asked, wrapping her arms around his neck. 

"I am sure that I do." Aiden answered. 

At first he had his own doubts and dilemmas. 

But over time, one thing became more and more clear. His love for her will never change. 

Anna smiled. 

'I love you too. So much that I want to protect you.' she thought inside. 

She couldn't save her son. So, she will do her best to protect his father. 

"Now, you need to tell me what is happening, Anna." Aiden said as he caressed her cheek. 

Anna didn't respond but hugged him tight and buried her head in his warm palm that's holding her cheek. 

It only made Aiden more worried. 

Noticing that someone is walking towards their direction, he carried her in his arms to a relatively quieter place.