And 100 years ago, your comment would read "I see a couple walking across campus, obviously walking together, but each staring silently at the sidewalk instead

And 100 years ago, your comment would read "I see a couple walking across campus, obviously walking together, but each staring silently at the sidewalk instead of talking to each other". Not every moment needs to be constantly filled with chatter, and if there's nothing to say, there's nothing to say. Sometimes just the act of physically being near each other is enough.