Jennifer Aniston's boyfriend loves her "natural" instinct to look after people.

The Hollywood star is currently in a committed relationship with Justin Theroux, with claims they are even planning to marry.

Jennifer is known for having close friendships, such as with her Friends co-star Courteney Cox. She was also there for Robert Downey Jr. when he was battling drug problems, and her caring nature is what first attracted Justin.

"She takes care of people. Jen has always been this warm, loving person who wants to be there for her friends, and it's like an instinct to look after the people in her life. Justin does understand that, and it's a big part of why he loves her so much," a source told Look magazine.

Jennifer has recently been in touch with her ex-boyfriend John Mayer, who has been forced to cancel some shows due to a throat condition. He is said to be very down about the situation so Jennifer has been checking in on him regularly.

"She must understand what he's going through if someone told her tomorrow that she couldn't act any more, she'd be distraught," the source added. "She and John have been speaking on the phone a fair bit."