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Due to Pauline's absence, Princess Toadstool replaced her as Mario's girlfriend in "Super Mario Bros." (NES). She re-appeared on Mario vs. Donkey Kong 2: MotM (DS) where Paulene is Mario's guest of honour and then DK kidnaps Pauline.

The MvDK2: MotM instruction manual states that Mario and Pauline are simply good friends at that time, and now she's Mario's ex-girlfriend.