A breakup is coming.

Sophie Turner accidentally played a part in a celebrity couple breaking off their engagement after a San Diego Comic-Con afterparty run-in years ago.

The 29-year-old actress shared with Seth Meyers on Thursday how her “pretty wild” night took a turn for the worse when a childhood friend requested a favor.

“She saw this actor she, like, loved,” the “Game of Thrones” alum explained on “Late Night With Seth Meyers.”

When Turner’s pal begged her to “say hi,” she simply waved at the man from afar.

“That was the turning point,” the Emmy nominee emphasized. “Later, I noticed a well-known actress staring at me and decided to approach her to express my admiration for her.”

Turner “dance[d] on over” to the woman — only for the unidentified A-lister to ask, “Can you stop f–king flirting with my fiancé?”

When Turner asked who the woman’s partner was, she “point[ed] at the guy” the “Joan” star had waved at.

Turner confessed, “I had no clue who this man was. It turns out they ended their engagement that very night because I waved. I never knew I had such influence.”

Turner noted that she couldn’t reveal the couple’s names or she would get “in trouble.”

Elsewhere in the interview, the “Staircase” star spoke about how “vile” it was to kiss her former onscreen sibling Kit Harington in their upcoming movie, “The Dreadful.”

She confirmed that her intimate scenes with the 38-year-old were “worse” than filming with cockroaches and a mouse in her latest release, “Trust.”

“We get on set and we are both retching,” Turner recalled of the “really bad moment in [her] career.”

As for her offscreen love life, the “Dark Phoenix” star has been dating aristocrat Peregrine “Perry” Pearson on and off since 2023 following her divorce from Joe Jonas.

She and the Jonas Brothers member, 36, co-parent daughters Willa, 5, and Delphine, 3.