I've never met DH's family. They've (by his accounts) had a rocky history, and DH says they're horrible people.
There was no one reason they stopped seeing each other, just that DH didn't want to travel to see them, and they didn't come here.
DH did add his sister on facebook 2 years ago, she commented on a photo of him & her, he then deleted her as a friend as she never emailed him, though he didn't block her.
As far as I know they think that DH is still married to his first wife, and they know nothing about us, or our toddler.
We recently lost our second child, and I know that DH felt bad that my family were at the funeral, but none of his were. I also know he hates how much support I get from my family, but he's too stubborn to reach out to his.
I will add I've never met any of DH's family (apart from his grown DC), nor his friends.
I'm half-tempted to contact his sibling on facebook, but I'm not sure