Parents, don’t withhold your warmth and affection from your kids significant others simply because you don’t know if it will work out long term or you’re worried about heartbreak.
You will be missing out and also depriving them of something that they might be looking for in the big picture, too.
OP, it sounds like things are good for both your D and her ex. I’m glad you were able to clear the air and reassure yourself and your D that the ex is doing OK and that she’s OK with you being there if the ex needs an extra ear. I’m sure with time, she will figure out what relationship (if any) she wants to have with the ex. My folks saved themselves a lot of heartache by not really getting to know the folks we dated until we were engaged. Since there were so many of us, that was a LOT of relationships that came and went through our lives collectively as a family.