I totally agree with you about smartphones but have never been able to figure out how to say it without getting shot down. You make great points.
If you think about one person having a whole 12-hour day to grapple with, you realized nobody constantly engages with other people for 12 hours straight. It would make us crazy. Before phones, people would be thinking through the things during their down times that they can know physically think through with their phones.
And the best part of being a couple is you can have your down time together. I don’t know any couples who spend every waking moment talking and interacting with one another. A lot of what happens in partnerships is similar to what we call parallel play with toddlers. There is great comfort in doing your own thing alongside a trusted partner and friend.