Some of the greatest songs are written out of pain, a pain that usually starts close to home; a broken relationship, a sparsity of emotion or reluctance to show it. Sometimes you can only say what you mean in a song.
A lot of people were lucky enough to be surrounded by love when they grew up, and that has flowed over into their lives, but others were not so fortunate. How many great songs are there about a stable, constant and open relationship with anyone? Would Harry Chapin have had such a great hit with 'W.O.L.D.' or the one where his son wants to be just like him, if they had been happy stories? My father died 2 years ago, and it took my mother 2 weeks to realise that she did not have to listen to the same radio station again, because he forbade her to change the settings, and refused to listen to anything other than local radio. Those are the real life stories that make great music. Where would the blues be without them?
I am genuinely sorry that you didn't get to say those words to your father, if mine had been different, I may have wanted to tell him too. But actions do speak louder than words. If you can't tell them, show them. A simple act like helping him with a cup of tea was enough for my father, it turned out to be his last, and I couldn't do any more.