I do have to wonder what led up to the divorce to begin with. Just from that brief look at the flashback, the father seemed giddy about the divorce, or maybe that was a wry smile as he was talking to his junior (maybe the same girl he's going to remarry with?). Meanwhile, the mother looked like an empty husk right up until their child started crying. Sure, the dad's taking responsibility for waking her up (if that was even his fault, didn't notice what he did that would imply doing so), but the mother's clearly at a breaking point if that much was enough to get her crying, as well. I don't know if the dad was giving enough support to the mom on top of helping looking after the child and making the income to support the family, but it seemed clear that neither of them were happy with the current status of their marriage.
One also has to wonder if the dad is giving the mother less opportunities to see her own daughter so she could get to know her soon-to-be new mom under the guise of giving the old mom time and space to get her life back together. As someone who grew up with divorced parents, myself, it breaks me to see the kid being used as a means to make or break a relationship like that.