Dad shocks Mom one day by saying he's moving out.  Mom finds another guy to marry, but discovers that his flaws aren't "correctable" after all, so she dumps him.  Dad comes back around flirting, but Mom isn't so enamored with the idea of getting back with the guy who dumped her.  So, she finds herself a young hottie who is super successful and treats her like gold.  She is now happily married.  Dad, meanwhile, finds himself some trailer trash who decides to use him for whatever she can get out of him in his last years. 

Would I hate Dad?  Absolutely not.  I'd still love him dearly, but I would lose a lot of respect for him.

Would you hate your dad if he had a fling with some young faloozie? Me I'd be happy for the old man!