It's always hard to say what causes distance in any relationship, but I know for me, I established very close relationships with my kids from the time they were tiny and especially into their teen years, and so far it has extended into their adult years.

For example, my son discovered he is allergic to marijuana. He was hanging out with friends, thought he'd try it and then began projectile vomiting. He was at his dad's house at the time, but called me for assistance instead of waking up his dad.

He then tried it again (just to make sure, I guess? Lol) and again, I rubbed his back while he was sick until it cleared his system.

We decided about a year and a half ago to live as a multi-generational family, so I have my 4 adult children (19-27) living with me as well as my son in law and my 2 grandkids (4 and 6). We created a community while they were young that was especially helpful when Covid hit.

My 27 year old daughter who has 2 kids of her own woke me in the night recently because she had food poisoning and just needed someone to support her in her time of sickness. Her husband commented that he would never wake his parents in the night if he was sick, which made me sad, but I think is a much more common sentiment.

I guess my point is, that bond has to be created when they're young. If it was, but they're pulling away now, maybe they truly are just busy. If not, it may be difficult to re-create.

You might try asking them if they have unaired grievances that are putting distance between you to make sure there aren't hurt feelings that need to be resolved. Every parent makes mistakes, and children are hurt by our mistakes, so it's necessary to go through the process of listening to, and validating, those feelings.