The 27-year-old singer and the brunette beauty recently called time on their ten-month romance, and a source close to the situation has revealed that it was The Weeknd who instigated their split.
The high-profile duo had rarely seen each other over recent months and because they both have jam-packed working schedules, they had hardly even been speaking on the phone, according to TMZ.
As a result, The Weeknd - whose real name is Abel Tesfaye - decided to end their relationship several weeks ago as he didn't see them having a long-term future together.
The insider also insisted that their split was completely unrelated to Justin Bieber, who has recently been spotted hanging out with his former flame.
Despite this, another source recently claimed that Justin is Selena's ''true love''.
In recent days, speculation has been rife that the 'Sorry' hitmaker and Selena, 25, could be about to rekindle their romance, with a source close to the situation saying that Justin has always been her ''soulmate''.
The insider explained: ''Since things ended with Justin for good, any other guys that Selena dated were placeholders.
''All the other guys were just flings. Justin always had her heart and attention. He was always her soulmate and her one true love.''
However, the same source also said that Selena shared something completely unique with The Weeknd.
The insider said: ''She met The Weeknd and all that changed - she [could] see a future with him and [felt] different about him than the other flings.
''She [had] been happy with him but Justin always has the biggest piece of her heart. The situation is a heart string type of thing. She has to figure out what she wants.''