Might

"Okay, her name is Sarah..."

"Wait, isn't she your sister?" She interrupted, asking to be clear because she knew he once said his sister's name was Sarah. 

"Exactly. My sister Sarah..." 

"Where is she now?" Lilly asked, showing interest to know more about his sister than she would have done if it was another girl from his past. 

"...that is going to be a very difficult question to answer, because I don't know how to start." He articulated inaudibly, slightly bowing his head down to think, looking sad at the same time. 

"Don't worry, I am okay if you start from the event that lead to your being separated from your sister because I could recall you told me..."