what's to tell? they got married, they got kids. you wanted to see how little Anthony was made?
I don't know if you ever saw another movie in your whole life, but usually time lapses in them and only significant parts of the story are presented to us. Seeing them with children makes us automatically aware we have made a jump in time, at least a year or two/three. I think it was a brilliantly used movie-element, so often used in films, since we don't need text to appear on screen to tell us we are a few years further.
it never bothered me either
what bothered me most is the total plot duration of The Godfather, which is almost 10 years!