"An ability to listen without judging.
Empathy.
Separation of emotions - where the mother doesn't project themselves onto the child and want the child to "be what I couldn't be"."

I like the sound of that bonaire. I wonder how a mother can give unconditional love since being a parent, by its very nature, means setting conditions or limits?

I do think once a child is grown and living on their own, unless they are doing something truly self or other destructive, a mother should try her best, just as a friend does, to get to know and understand who her child is (and accept them), not who she wants them to be. I think it can be difficult as a mother if a child is living a lifestyle and has values very different from hers. It's easy to find yourself judging rather than loving. Tricky business, love of any kind, in my experience.