I recently came across a reddit comment explaining that Jenny treated Forrest Gump like shit because she loved him too much. It's a pretty well-though-out comment and sounds like a good explanation unless you consider an alternative: Alpha Fucks; Beta Bucks. It's almost a textbook example of AF;BB. She rides all the dark triad cock she can until she needs someone to take care of her son who was conceived from a pity fuck. She even marries the guy right before she dies, but not until she can no longer get AF and Forrest "got more money than Davy Crockett".

I look forward to a day when TRP philosophy is so widely accepted in Western culture that AF;BB is inherently obvious to anyone with half a brain. Actually, scratch that; I hope every man but me swallows TBP :D