This happened to my 70 year old mom. When her boyfriend (common law husband) of 23 years passed away of cancer, his family froze her out and never saw her again. For all those years she considered his adult kids her kids, and his grandkids her grandkids. She bought them gifts for every birthday and Christmas and celebrated holidays with them and hosted holidays and parties at her home. She loved them. 
 Then...nothing. They never contacted her again after he died. It was heartbreaking for her. I mean - how two sided can you get. She loved them and thought they liked her. But it turns out they were just tolerating her. So phony. And cruel.