WARNING: The following article contains spoilers for Uncanny X-Men #5, by Matthew Rosenberg, Kelly Thompson, Ed Brisson, R.B. Silva, Adriano di Benedetto, Rachelle Rosenberg and Chris Eliopoulos, on sale now.

More than almost any other superhero team, the X-Men are built around relationships. With a deep bench that includes dozens of major superheroes and hundreds of second-tier characters, the X-Men mythos also serves as the backdrop to some of the most long-lasting romantic relationships in the Marvel Universe.

While Marvel's mutants' more romantic moments usually involve Rogue and Gambit, or some combination of Wolverine, Jean Grey, Cyclops and Emma Frost, the relationship between another major X-couple, Angel and Psylocke, just changed... "forever."

RELATED: A Major X-Man Just Lost Their Iconic Weapon (And Got Two New Ones)

While the two X-Men were attending a political rally together in Uncanny X-Men #1, Angel was seemingly summoned in the middle of a riot by an unseen force. A few issues later, he returned as a seemingly brainwashed Horseman of Salvation, a servant of the would-be world savior, former X-Man and ultra-powerful telepath Nate Grey.

In Uncanny X-Men #5, Angel and the other Horsemen are fighting a small group of X-Men. In a desperate attempt to free her on-and-off romantic partner from Grey's control, Psylocke attacks him with the telepathic sword that represents the focused totality of her psychic powers.

Psylocke Angel slash

But instead of restoring Angel's mind back to normal, Psylocke's blade transformed him into Archangel, his vicious, blue-skinned alternate persona.

While he tells Psylocke that she's "ruined [him] forever," only time will tell how permanent Angel's transformation back into Archangel will really be. However, even if it ends up being undone swiftly, this moment still marks a significant boundary crossing for two characters with complex and oddly similar histories.

Archangel reborn

Before they joined the X-Men, both Warren Worthington III and Betsy Braddock grew up in worlds of generational wealth and privilege. Before joining the X-Men, both mutants already had burgeoning superhero careers of their own. Warren briefly worked as a solo hero called the Avenging Angel, and Betsy helped out her brother, Captain Britain, on his superhero adventures.

While the high-flying Angel was one of Professor X's original X-Men in the 1960s, the telepathic Psylocke was one of the team's core members throughout the 1980s. During their stints with X-teams, both Angel and Psylocke went through dramatic physical and mental transformations that turned them into twisted reflections of their former selves.

RELATED: Jean Grey Saves the Day With the Most Powerful Force in the Marvel Universe

Shortly after the X-villain Apocalypse debuted, he transformed Warren into Archangel, his Horseman of Death. With this transformation, Angel traded his feather wings for a pair of razor-sharp metal wings, blue skin and the savagery of a supervillain. While he eventually overcame Apocalypse's programming, Warren has struggled to control the Archangel persona within for decades.

On a similar note, Psylocke was transformed by Matsu'o Tsurayaba and the Hand. In a controversial storyline, the mind of Betsy was placed in the body of Kwannon, a Japanese assassin. Although she quickly overcame the Hand's brainwashing, she acclimated herself to using her newfound ninja skills, psionic blade and more aggressive killer instinct over the next several years.

After both of these X-Men became more famous in their post-transformation forms, Angel and Psylocke began their off-and-on relationship in the early 1990s. When both were members of Uncanny X-Force, their relationship came to a head in Rick Remender, Mark Brooks and Jerome Opeña's "The Dark Angel Saga." To stop the villainous Archangel from killing the world, Betsy attacked him, apparently fatally, and telepathically gave him false memories of growing old together.

RELATED: Marvel's X-Men Enter the Age of X-Man With 6 New Series

While Warren survived Psylocke's attack, he was left with temporary amnesia and struggled to control his Archangel persona after that. Earlier this year, the recently-revived Professor X gave Warren complete control over his Archangel persona. Not long after that, Psylocke transferred her mind into a new version of her original body too.

Although both X-Men were in a place of relative stability for the first time in years, any chance of reconciliation were shattered when Angel fell under Nate Grey's power. In an effort to restore the man she once loved, Psylocke unwittingly unleashed Archangel. In doing that, Betsy may have very well shattered the peace that Warren had been seeking out for most of his adult life, and she'll have to live with the consequences of that potentially unforgivable action.

While it's not clear how long Archangel will stick around, or how Betsy will respond to his presence and harsh claim, they'll both continue to appear in Uncanny X-Men, which is being released weekly by Marvel.