Because we lead fairly dull lives, we have a very good idea of where the other is at any given time. There just isn’t much to keep track of! This has been true since we were “serious” about each other, not just living together and then married. We do things without each other on occasion, but even then we know who is where.
In terms of autonomy, I’m my own person and he is his own. If I want to do something with my girlfriends, I make sure we don’t have anything planned before I say yes to anything else. He does the same with me. I think it’s about being respectful of each other. We can go do whatever strikes us, we just check on the when. As an example, I’m planning to visit girlfriends over Columbus Day weekend. I will call him when I get there so he knows that I’m safe. Then once to say goodnight. I might call when I start my drive home, but that depends on how early I leave. Or I’ll call if I’m getting close to home and we might want take-out for dinner.