Mei has never blamed Jack, not really. Her shadow certainly did, but Mei knew Jack had his own problems to deal with in running for his life and trying to uncover this conspiracy that ended Overwatch single handed. The people that are to blame for this do make her angry, but there's nothing she can do with that anger here, so she can only be sad instead.

"Oh, a dog? Tell me about it! Male or female? What breed?"