Honestly, This Could Have Only Been Written By A Woman
Overall I like this movie. But the idea that Doug would only be consumed with chivalrous rage toward his brother but not jealous rage toward Pam is a little far fetched. That's just not how guys are--that's how women want to believe guys are.
And he blew an opportunity with Elanor at the airport! She started out acting all flirty with him but then he started going on about his mother and Pam and she got cold on him. He probably could have nailed Elanor. That would have made it all even--both Doug and Pam would have gotten horizontal with one of eeach other's siblings. Clean slate. That would have feeed up any jealous feelings or shame and Pam and Doug could have lived happily ever after.
That's the only way they could have overcome Pam nailing Jacey in real life. Call me cynical, but I think I'm just a realist.