Sorry I don't know the history of this. But I have something of a similar experience, but from the other side.
When I met my now-wife, her daughter lived with her ex-husband. Things started out OK, she stayed with us every second weekend and half the holidays. Things changed when we went to pick her up one day and casually mentioned that we had got married. I don't know what trigger this sent to her dad, but after that he stopped our access completely. We went to court and all that jazz but there was a time (again, about 15 months or so) when we didn't see her. We saw her when she was 4 and a half, then again when she was almost 6. That's a big chunk of time to miss.
This is all ancient history now of course. But over the years we missed out on huge chunks. I won't go in to all the ins and outs but we eventually got to the place where we thought "she'll come to us when she grows up". We became these strangers who would sometimes visit but had no real connection with her.
Fast forward to last Christmas and she moved out of her dad's place and now lives 5 minutes from us. There's still a big emotional distance though. We saw her yesterday and to be blunt, we have small talk and not much else.