Another aspect to remember along with those that Heather has pointed out is that all of these members of the family work in the same place called the "Firm". Its not a operation run by a "boss" that tells everyone what to do, how to do it and when to do it and where but its a family that has pretty much equal input into how things are done in relation to what they do.
In "Our Queen" by Robert Hardman, Andrew says of the "Firm" that "Its rather like having a business which has a number of diversified subsidiaries. We do our thing and we conduct our lives but occasionally we come back and talk to the the boss of the parent company." "We're all off doing things and then there are moments when we get together in an environment where there are lots of other people and they suddenly notice that all of us are having a conversation because we haven't actually been together for three months. Its entirely because we are performing roles in support of the Monarchy."
Its no wonder then to me that there are times in all of the royal's schedules that are set aside to actually interact as a family. The Christmas Lunch for all of the extended family, the Christmas celebrations at Sandringham, Easter at Windsor with Trooping the Color after and Ascot Week and the summer sojourn to Balmoral. These folks have to plan in advance when they all can get together simply because their lives are so filled with their work for the monarchy, their own personal endeavors and as time passes, their own families. These are people that know what they're going to be doing a six months to a year from now already as its penciled into their personal planners.
This is also a family that just doesn't "drop by" to see an aunt or a brother or a family member on a whim because chances are that the other person is slated to be somewhere doing something at that time. The Cambridges and the Sussexes may be able to "drop by" more often than most simple because they do live in close proximity to each other and have office space in common but that, too, is changing as the brothers and their spouses turn more and more into the diversified subsidiaries that Andrew was talking about. It comes with the territory to being full time senior working members of the "Firm".
The culprit I think in all the changes that are coming about is not the interpersonal relationships between William and Harry and their spouses is totally due, I believe, in the changes these people have had to make in taking on their roles as full time senior working royals. They're no longer really going to be walking the same paths as before when we've seen the unity of the Royal Foundation but taking on diversified roles of their own along with remaining strong within the Royal Foundation.
It's interesting to watch them grow and expand and to me, its all part of a soft transition to prepare to continue seamlessly as the new reign becomes a reality that is going to be sooner rather than later. It points to a well oiled machine that knows where its going and how it wants to do things and is prepared for any event that may come.
This is the "normal" of the British Royal Family. Its not quite the "normal" that we know family to be.