Lohan's boyfriend was engaged

Lindsay Lohan stole new boyfriend snowboarder Riley Giles from his fiancée - according to the girl's mother.

The 21-year-old actress confirmed reports she is dating the California-based X-Games star earlier this month, after leaving the Cirque Clinic rehab facility in Utah.

But Giles was already engaged to Utah resident Bree Tierney - and news of his relationship with the Mean Girls star has left her heartbroken.

Tierney's mother, Tess, says: "Riley just stopped calling Bree and never told her about Lindsay.

"She found out by seeing photos. It destroyed her."