Before Darlene's wedding, she has a heart-to-heart with her father, in which he talks about her future and avoiding lost opportunities. The anguish and resignation in his voice is more poignant when you realize that from the last episode, we find out that this takes place just before his fatal heart attack.
Darlene: I'm not going to miss any opportunities. David and I are still young enough, so they'll be plenty of time...
Dan: No..nononono, you see that where you're wrong, Darlene. Everything thinks that there is plenty of time to do whatever they want. Believe me, there's not. Stuff happens.
Darlene: What stuff?
Dan: I don't know. Any kind of stuff. All kinds of stuff. See, you plan things, and the clock keeps ticking, and you never do them. And, suddenly, DJ's in high school, and you're having a baby...I haven't talked to my dad in two years.