Kiefer SutherlandKiefer Sutheland and his longtime girlfriend, Siobhan Bonnouvrier, have called it quits.

Us Weekly is reporting, after almost three years together the two have gone their separate ways. A source close to Bonnouvrier dishes, "They've split for now," going on to explain that things are "transitional and ever changing."

Bonnouvrier, the style director at Allure magazine and the '24' actor began dating in 2008 and sparked rumors of an engagement while on vacation in Italy last summer. Bonnouvrier was spotted wearing what was thought to be a sparkling engagement ring, but nothing ever came of the speculation.