Liam Payne’s girlfriend, Kate Cassidy — who was with the One Direction singer just days before his death — is reeling from the tragic loss.

A friend of the influencer exclusively told The Post that Cassidy is agonizing over her decision to leave Payne alone in Argentina before he fell to his death.

“She did what she needed to do at the time,” Cassidy’s pal said. “She had no idea what was going to happen. I can tell you that her decision will haunt her for the rest of her life.”

“She feels bad. Everyone in her life is saying that it’s not her fault,” her friend continued.

“You can’t babysit a 30-year-old grown man 24/7/365. But she’s not yet in a place to hear that.”

Two days before Payne’s fatal fall from a third-floor balcony at CasaSur Palermo Hotel, Cassidy shared a TikTok travel vlog revealing she had left the South American country.

In the video, she said they were initially only supposed to be in Argentina for five days, but the trip turned into a two-week getaway.

Cassidy’s friend told The Post that after leaving Argentina she attempted to convince Payne to also return home to Miami after she suspected he was on a bender.

“She tried, really. But he wasn’t receptive,” the pal said. “She will forever be the villain for abandoning him, but that’s not what happened.”

The friend said Cassidy “planned a certain time away from home and he wanted to extend it indefinitely.”

Despite their apparently fun vacation, which he documented on Snapchat, “She wasn’t ready to do that.”

The influencer — who was first linked to the musician in October 2022 — was simply homesick.

“She wanted to be home in her own bed with her dog,” Cassidy’s friend further explained. “She wanted to come home.”

Her friend even claimed Cassidy felt like she was in a “hostage situation” prior to her departure from Argentina.

“So she tells him she wants to leave, this is after a week. He begs her to stay,” the pal told The Post. “She keeps extending her trip, a day, two days. And he just wants her to stay, stay, stay.”

The “Teardrops” singer died instantly on Oct. 16 after falling from his hotel balcony, per the Associated Press. He was 31.

Payne suffered multiple traumas, including a cranial fracture, that led to internal and external bleeding.

A partial autopsy revealed he had cocaine, crack, benzodiazepine and “pink cocaine” in his system at the time of his death, sources told ABC News on Monday.

In a tribute shared on Instagram Wednesday, Cassidy revealed she and the late One Direction alum had plans to get married before his death.