Liam Payne's partner, Kate Cassidy, the member of One Direction who recently passed away, had left her boyfriend alone shortly before his death. During the last days in Argentina, according to

A source close to Kate Cassidy tells PEOPLE exclusively that Liam Payne's "erratic behavior started ramping up" when she left Argentina, where they were on vacation. The One Direction alum died on Oct.

Liam Payne's girlfriend Kate Cassidy left Argentina and returned to the US just days before the singer died after falling off a balcony.