User blog comment:Zathronas/Analysis by an author: Volume 2 episode 6: Burning the Candle/@comment-181.208.226.194-20140905032518

I, for one, was completely wrong about the whole subject.

My original theory was that Summer got pregnant of Ruby, but didn't had the courage to tell the father. He, on the other hand, got married and had Yang, which was also one of the reasons why Summer never told him the true. Then Summer dies, but she had pronouced Mr. Xiao Long and his wife as Ruby's legal guardians.

In the end, It wasn't Summer who left, but Yang's mom.

HSXI.