One of the things that's really striking about this scene, every time I've watched it, is that Ennis looks tired but not particularly unhappy, and that he doesn't even need Alma to ask him to look in on the babies, he just does it. And in the later scene, he's obviously the one who puts them to bed at night (or at least some nights). Very unusual for any young American father in the mid-1960s. It gives you a glimpse of the kind of man Ennis could have been.
Ironically, when the film first came out I read some angry essays mentioning this scene as trying to show heterosexual marriage and family life as being "squalid." (Part of the Gay Agenda, donchaknow)