If I write down all my friends' birthdays on a calendar and use that as a reminder to get in touch, is that shallow? Some of us are just bad at remembering these things.

Also, when you work 60+ hours a week, have a kid, have a partner with whom to maintain a relationship, and spend an astonishing amount of time on chores, it's not shallow to just get distracted. For what it's worth, people remember, I think, just not as often as they'd like.