Save the Day, Turn Away

You defeated the villains who Cursed You With Awesome—saving your loved ones in the process, turning some cynics into optimists, and using the only antidote for your mutation to selflessly cure the Littlest Cancer Patient. Your love interest still wants to be with you, even with your transformation and new powers... but you don't exist anymore. You're a freak. You tell her the man she loved is gone, you're something else now, and you leave. She cries your name as you walk away into the night - to save the innocent and help the helpless.

Mostly found in Sci-Fi or Superhero films. Variation of But Now I Must Go, sometimes coupled with That Man Is Dead.

Type 1 - Physical: The protagonist either is a newly-minted superhero or has transformed into a hideous yet benevolent creature. He must abandon his initial goals and romance to either walk the hero's path alone or find a means to counteract his current transformation (good luck with that). The hero must tell his love interest that the man she loved is gone; only the heroic persona or hideous yet benevolent creature remains.

The hero must abandon his love interest because his very presence will deprive her of the normal life the love interest deserves. In the more optimistic and less creature-related examples, he must also leave because their love interest will never be safe from villains if he stays.

Type 2 - Social: The hero purposefully denies or is denied acknowledgement of his actions for the greater good of society.

Whatever type is invoked, it's helpful if it is followed by an emotionally resonant and important monologue.

Anime and Manga

 * The OVA Guyver: Out of Control features Sho Fukamachbi playing a variant on type one. After rescuing his Childhood Crush Mizuki, he brings her to a small overlook where she awakens to see him, in Guyver form, and almost instantly manages to deduce who's behind that odd alien mask. (and bear in mind in Guyver form the guy is at least seven feet tall, not counting the horn on the head of the armor from all we can see) He stands up and looks into the sunset, then turns around, and walks off not saying a thing to her as she desperately screams/pleads for him to come back. The epilogue says Mizuki went back to school and was fine after that, but Sho himself is never seen again. Presumably he and Guyver III continue their war against Chronos in secret but nobody knows it.
 * Tengen Toppa Gurren Lagann, with, of course, in type two. Course, he's actually just leaving his more responsible friend in control of the government because he's a wandering hero type.
 * Or he doesn't want to break his word not to use Spiral Energy and thus avoid accelerating the death of the universe.
 * Aya in Weiss Kreuz walks away from his beloved little sister and the girl who has a crush on him at the finale of the first series, after saving both of them from the Ancient Conspiracy and their Psychos For Hire, because it's the only way he can protect them from the life he leads as an assassin.

Comic Books

 * Inverted with Ben Grimm/The Thing of the Fantastic Four. He constantly deals with the fear, rejection and scorn of the world at large because of his rocky exterior, however he actually found love after the transformation into the Thing with blind sculptress Alicia Masters. Though he is very protective of her, as a Super Villain's daughter her odds of an uneventful life are already low.
 * Also, in at least a few stories, he's less likely to terrify passersby than he is to be mobbed by people wanting his autograph; being a member of one of Marvel's most prominent superhero teams for a couple decades does that to a person.
 * Ben Grimm is often known as 'The Idol Of Millions', and is one of the most popular heroes in the Marvel Universe. His fear of rejection mostly stems from self-loathing due to his appearance, and early encounters before his fame took off.
 * Batman - At the conclusion of Batman: Year One, Batman (who is unmasked) saves Jim Gordon's Baby. Jim Gordon has suspected Bruce Wayne of being Batman throughout the whole arc. Gordon tells him that he's blind without his glasses, and that he should leave him before the police arrive. Batman leaves. Whether Jim was lying is unknown, although other stories hint that he might know.

Film

 * Swamp Thing - Dr. Holland saved Alice and Jude, even killed Dr. Anton Arcane, but due to his botanical transformation Dr. Holland can never continue his work or be with Alice.
 * The Toxic Avenger: subverted optimistically, Melvin's transformation into a hideously deformed creature of superhuman size and strength has improved his social life, his standing in the community, and is generally beloved and worshipped as the first superhero from New Jersey.
 * RoboCop 2 - The movie begins with OCP's legal team forcing Murphy to turn away from his wife and kid. Murphy doesn't want to give up on trying to connect with them, but his family are freaked out by his visits to their home - and are threatening to sue OCP - so Murphy lies to his wife and convinces them that he isn't really her husband reborn as a warrior of living steel, but a robot built in honor of Murphy's memory.
 * Darkman - Darkman leaves Julie because he isn't Peyton anymore, he's Darkman now.
 * Done again, MUCH more sloppily (seemingly in great haste at the very last minute of editing) at the end of Darkman III.
 * Fluke - The hero having saved his child, he lets his ex-wife know that he was her husband. But he must leave his family because he is no longer Tom; he is a dog now.
 * Blade - The Daywalker kills Deacon Frost and saves the girl. He refuses to take the serum to cure his special blend of vampirism because there are more vampires that need killing, and he's going to be the one to do it.
 * Spider-Man - Peter kisses Mary Jane and leaves her because he is Spider-Man now. Subverted by sequel.
 * Batman Begins - Inverted, Rachael leaves Bruce. She leaves him because he isn't Bruce anymore... HE'S THE GODDAMNED BATMAN!!!
 * Superman Returns - The Man of Steel realizes that his continued presence in Lois Lane's life would be problematic and confusing
 * Ghost Rider - Johnny defeated Blackheart, but realizes that he can never have a normal life with the woman he loves. He use the spirit of vengeance to fight evil and walk the hero's path.
 * The Dark Knight - Batman saves Gordon's family from Two-Face in a massive homage to Batman: Year One . Batman decides to take the blame for Two-Face's crimes as a means to maintain Dent's legacy. Gordon and his son plea with Batman not to take the blame but Batman flees into the night while Gordon's son calls Batman's name. Gordon helps cement the trope by delivering a heroic monologue on behalf of Batman.
 * Watchmen -

Literature

 * In The Dresden Files,, joining a band of other Friendly Neighborhood Vampires who are fighting their hunger as well as evil vampires. (Since Our Vampires Are Different, a person who has been turned doesn't become a full vampire until they feed for the first time. Until then, they're still themselves, and though the hunger is felt, they don't have to feed to survive.)
 * Harry Potter himself attempts this with
 * Stationery Voyagers runs the whole gamut with this.
 * Inverted in that Arnold "Pextel" Rubblindo faces constant rejection from his mother over the fact that he was turned into a robot.
 * Subverted to Hell when Pextel not only can't use it on Pinkella due to her being a core team member, but when it would do absolutely no good because she doesn't care if domestic partnership to a robot means perpetual virginity.
 * Totally averted with Rhodney, Oceanoe, and Marlack.
 * Played straight with Neone in relation to her Shinroff parents; yet averted with her relationship to Marlack. Then again, her biological parents are completely understanding of her decision to keep her last name of Delft.
 * Inverted with Liquidon; he returns to his home world to find out that nobody cares how often he saved it. He is ultimately only thankful they don't try to prosecute him for causing some of the mess to begin with.

Live Action TV

 * 24: The series ends with Jack Bauer having to leave the woman he loves after he saves her, because she will always be in danger if he stays... That woman is America.
 * Robocop The Series: At the end of the pilot episode, Murphy saves the city and comes to the conclusion that his wife and son must never know that he is Robocop. He knows that he can never act as a husband and a father to them, but he can be their savior.

Video Games

 * Splinter Cell:Conviction Sam pulls one on Anna after saving the president.
 * Ryu at the end of Street Fighter II.

Western Animation

 * Spawn - Spawn saved his widow Wanda's daughter Cyan from the clutches of pedophillic serial killer Billy Kincade, and defeated him without killing him. Spawn realizes Wanda is happy with her new husband and their daughter and that his dream of being present in Wanda's life would largely be a downer. So he lets go, but not before he hands Cyan his wedding ring, and tells her she should go to her mother. Wanda is reunited with Cyan who simply tells her that she was saved by "the sad man". Wanda finds that Cyan is holding onto the wedding ring, she realizes that somehow the "sad man" is her dead husband. Spawn watches Wanda's reaction from afar, and then executes a textbook example of turning away.