What kind of dad was this man then? What kind of connection did he build with his daughter?
It's so obvious from what you wrote, yet it's interesting you seemingly didn't draw the connection. edit: it may be also that your friend herself did not draw this connection or is unconsciously avoiding it.
So, so much happens behind closed doors, in every home. So much unwritten history. So much that you'll never know about someone.
We all want to love our parents and feel it is the right thing to do. Yet to heal trauma, to heal depression... you have to acknowledge the anger that has built up. Legitimate anger of being ignored, insulted, ridiculed, abandoned, shamed, and so on. Paradoxically.. it is through gradually allowing oneself to feel this anger, that the heart opens.. and we are able to love again both self and others.