I don't think that the woman he is holding hands with at the march for Yingying is his wife. There is a picture of BC and his wife in one of the articles, and while her face is pixilated out, you can see that she has very dark hair. The woman at the march with him looks like she has lighter hair. I wish that the articles would think to pixelate her face out as well. I guess people that know her would recognize her, but I'm sure its difficult to have pictures out there indicating you have what looks to be a close relationship with a man who has been arrested for the abduction of, and likely murdered, a woman.
Link to article with picture of BC and his wife:
http://heavy.com/news/2017/06/brendt-christensen-yingying-zhang-brent-facebook-photos-suspect/