Board Thread:FAQs/@comment-92.238.201.230-20161029181455/@comment-4010415-20161123031619

Plus, think about it... Ruby was just a little kid when Summer died/disappeared, and when that happened, Tai shut down from depression. He wasn't much of a father when he was shut down. Qrow probably stopped by from time to time to help take care of Ruby and Yang, so Qrow probably ended up being more of a parental guardian during those days than Tai did. So, of course Ruby would end up looking up to him.

That, and the manga seems to imply that, when Yang took Ruby out into the woods to look for clues about Raven, Ruby woke up as the Beowolves were attacking and saw Qrow save them.