Peter Parker and Mary Jane Watson

Spider-Man 3

Both Mary Jane and Harry now know that Peter is Spider-Man. In the film, Peter is intending to ask MJ to marry him. When he reports the good news to his Aunt May (Rosemary Harris), she is delighted and asks Peter to give her engagement ring as a gift to Mary Jane. However, Peter becomes slightly overconfident due to Spider-Man's success. Meanwhile, Mary Jane's Broadway debut takes a turn for the worse when her performance gets bad reviews. Unaware of this incident, Peter accidentally pushes Mary Jane away, thinking he understands her situation. She also begins a rivalry with Gwen Stacy (Bryce Dallas Howard) for Peter's affections. Having been replaced on Broadway by her understudy and then having to work at a jazz club, Mary Jane and Peter's relationship worsens when Spider-Man is unexpectedly kissed by Gwen Stacy in front of a whole crowd of people the same way Mary Jane kissed Spider-Man in the first film. When Peter attempts to propose to Mary Jane that same night, Gwen appears at the same restaurant and flirts with him; Mary Jane leaves, furious.

Mary Jane, feeling alone and despondent, calls Harry, who recently lost his memory and hatred of Spider-Man after being defeated in an aerial battle as the New Goblin. They renew their bond, and in a moment of joy, Mary Jane kisses Harry. Realizing what she is doing, Mary Jane quickly leaves; the emotional turmoil restores Harry's memories and his mission to destroy Spider-Man as the New Goblin. He confronts MJ in her apartment, and threatens to kill Peter if she does not break up with him. Following Harry's orders, she breaks up with Peter. Peter, heartbroken and upset, refuses to tolerate these tragedies, and turns to the symbiote suit, which enhances his aggression.

One night, Peter decides to go to Mary Jane's jazz club with Gwen. He shows her up on stage by playing the piano, and makes a big show of dancing with Gwen. Gwen, realizing that she is being used as a prop to make Mary Jane jealous, apologizes and leaves. Mary Jane is still visibly shaken when Peter confronts her at the bar, and he is assaulted by two of the club's bouncers. A fight ensues, and Mary Jane tries to stop Peter. Thinking she is another bouncer, Peter strikes her. Peter, realizing what the evil symbiote is trying to do, leaves the club.

Peter tears the symbiote off his body at a church bell-tower. During the struggle, it falls on Eddie Brock, Jr. (Topher Grace) standing below and creates Venom. At his apartment, Peter fears that even though the symbiote was responsible for current events, he may not be able to put Mary Jane first, and gives his wedding ring back to Aunt May, who convinces him that if he tries his best, he can put things right. Peter then goes to Harry in desperation, because he needs help against his new foe. Harry turns him down, but changes his mind after his butler reveals that Norman Osborn had in fact killed himself. Meanwhile, Venom kidnaps Mary Jane, holding her hostage at a construction site, where a climatic battle takes place between the team of Venom and the Sandman (Thomas Haden Church) against Spider-Man and Harry Osborn, a.k.a. the New Goblin. During the fight, Harry defeats Sandman, but is impaled by Venom with his own glider. After Spider-Man defeats Venom, he goes over to the mortally wounded Harry, alongside whom Mary Jane is also present. Harry dies in Mary Jane's arms, mending his friendship with Peter in his dying breaths.

After attending their friend's funeral, Peter and Mary Jane reconcile.