Jennifer Aniston and Vince Vaughan have reportedly begun a no-strings-attached relationship.

The news emerges after the 'Wedding Crashers' actor was seen leaving Aniston's house after spending the night.

�It�s no big deal if he stayed over. They are friends and can be friends with benefits" a friend of Vaughan told Us magazine.

The couple famously dated following Jennifer's split with Brad Pitt.

�It�s difficult for people who have been in a sexual relationship to remain friends,� L.A.-based psychologist Ava Cadell added. �So the fact that they did remain friends really shows good character and stability.�