She may not be an animal or child. But don't forget, what she went trough all those years! All her life locked up in that castle acting dumb and barely ever looking up. Only know stuff what she heard and read. Everything else is new. If they ever find out that she's actually sane, they may as well take advantage of that! She won't know any better than a child would in situations of danger. She's still learning and her husband have any right to worry about her. Though tbh, a little to much LOL. But still, in her situation she does need permission. So they can plan out accordingly and think of her safety!
Only until all the political matters and other things are solved, can she finally be more free. With guards of course.

She’s not an animal or a child. She doesn’t need his permission to leave..