I 100% get you @mindsetchange I've got two daughters. (mid to late 20s.) One lives 20 miles away and one lives 30 miles away. I'm in my mid 50s and so is DH ... They have both been to university, they have both got partners - one is married, they have both got successful professional careers, and they both bought a house with their partner within the past 2 years. They have many friends, and very busy lives.
They can easily go three days without any contact. I do send WhatsApp messages - and sometimes they will answer within five minutes sometimes it's 3 or four hours, occasionally it's several days. I do see them on Twitter and Instagram. quite a lot, and they don't respond to me for a couple of days, which I do find a little bit irksome ... I think 'well you have the time to post on here, but not to send me a quick whatsapp message back?'
But I know they don't do it deliberately. Something else probably comes up as they are about to message me.
They've both got about 20 friends each. (I'm not kidding you!) From college and school and uni. and very, very full lives. They travel a bit with work, and they go away a lot - abroad on weekend trips, and to London, Edinburgh, Brighton, Bournemouth, Devon, and other places where they have old uni friends, and other people they know. It's can be a bit hard to pin them down for a visit, and we have to plan it several weeks in advance! I gave up phoning them to have a chat, because they never EVER answered.
They visit us about once a month and we visit them once a month in between. So we see them every two weeks if you see what I mean. We go a day trip together. (Me, DH, and the 2 DDs,) to the beach - in the summer, and we will go to see a show another time, and we will go for 2 or 3 meals together during the year. (Their husbands don't come on the day trip, and will come to one of the meals.) Neither of them are planning on having any children anytime soon. Although probably they will one day. The older one says she would like one in about five years.
We go to the oldest DD for Christmas day, for a couple of hours, (because she lives in the middle of me and DH, and our youngest.) Me and DH leave on Christmas day at about 1pm and have the rest of the day/our Christmas meal on our own... They all come to ours for Easter, and spend 2 or 3 ours on Easter Sunday with us.
Upshot is, they really, really, really don't need me (or DH,) and it does sting to be quite honest with you. I know it's natural, and I feel me and DH must have done a good job for them to be so independent and successful. But it makes my heart a little bit sad that they don't need me, for anything...
Not far from me, there's 4 or 5 families who have got between 15 and 20 family members within 15 minutes walk - and they're always popping in for coffees, going for a walk together, going on a day trip together, (two or three times a week for the six weeks during the summer holidays!) Going to the bingo together, having big family BBQs in summer, and all the little cousins play together.
3 of 4 generations of family are all there for each other all the time, and they gather at the gran's - or great gran's for special occasions and have big family parties. I do get so envious of this and long for my daughters to live closer to me and DH, and have a couple of kids each, and have the kids running to my house, to come and see nan and grandad for an hour or so. I would take them to the zoo or the woods or the park and play with them, and bake cakes with them, and have a great time. 
I grew up with this situation - living close to about 20 family members and they'd all pile into my nan's house on Christmas Day, and go to the oldest uncle's house on Boxing Day for a great big family get together, about 30 people. Me and my cousins would play together at uncle's house on Boxing day, and me and my friends would play outside on Christmas day with our new bikes/scooters/skateboard etc.
Quite honestly, it was a magical time and it's not like that anymore. But I know our DDs do love me and DH so much - and there's nothing they wouldn't do if we asked them. (And the same for us with them.) They speak to me a few times a week on Whatsapp. and I communicate with them on Twitter and they message me back - and as I said they do visit, and we visit them.... and see them twice a month, and I know they'd be here in a heartbeat if we needed them urgently. And they're only 30 to 40 minutes drive away after all.
But yes, I really, really do wish that they were a lot closer and I do feel a little bit woeful and envious when I see the families in my street that have all their family members within 15 to 20 minutes walk. I long for that ..... Maybe one day.... Maybe when my DDs hit their 30s, and they have kids, they will need me and DH more, but right now they don't need us at all. I remember the wonderful days, when they were tiny, big-eyed infants, and I was the centre of their world. Now I'm just on the edge of it, looking in.
And oh, how I miss the wonderful, magical CHRISTMASSES with them, when they were little. 😄 Going to Santa's grotto, and lots of different Christmas events and places, and driving around looking at all the Christmas lights, and taking them to the big indoor shopping centre in the evening for the late night shopping, a few days before Christmas. Such wonderful days.