Hailey Baldwin told Justin Bieber he had to be monogamous if he wants to date her, it has been claimed.
The 19-year-old model was first romantically linked to the 21-year-old singer last year, with the pair confirming their romance during a New Year's holiday.
Following their vacation, it was alleged that Justin had been hooking up with Kourtney Kardashian - something Hailey was not impressed about.
A source said: "She demanded he stop stringing her along. She said he would lose her if he didn't man up and show he was serious about her."