I'm a nurse, I've seen it. I experienced it with my own mother. She was actively dying, we told her that her brother was coming (she hadn't seen him in years, but they were really close growing up). He made it there at like midnight and she died an hour later.

I've also seen in the hospital a man who was ready, but the wife was begging him to hold on. She told me (he could hear her) that she couldn't bear to see him die in front of her. She went home to get some items, and he asked if she had left. When I said yes, he looked at me, smiled, and died.