An insider on the set of her movie Jennifer’s Body says that the 22-year-old didn't act like she was taken. “I’ve never seen her wearing an engagement ring. I actually thought she and Adam Brody, who’s also in the movie, were dating. They were very flirty with each other and were always hanging out together when they weren’t working.”
Looks like Megan Fox is taking the passive aggressive road to letting her boyfriend Brian Austin Green down slowly. She wants to break off their engagement but doesn't want to break his heart, so she might try being so annoying that HE wants to call it off. She started the ball rolling by wearing her engagement ring only intermittently.
No luv – Fox & Green

Fox & Labeouf – Soon?
If Brian eventually gets fed up with her behavior and takes a walk, she wouldn't have to feel so guilty about having that crush on her Transformers costar Shia La Beouf as well.
Source: Hollywood Newsroom, Janet Charlton's Hollywood & Sunday Mail UK
Related: Megan Fox & Shia Labeouf: 2/3 of a Love Triangle
{mosgoogle}

Megan Fox have broken off her engagement to former Beverley Hills 90210 star Brian Austin Green. She turned up at the MTV Movie Awards without fiancè Brian Austin Green and without her engagement ring. In fact, the Transformers babe hasn’t been spotted with the ring for months, sparking rumors that she and the onetime Beverly Hills 90210 star are on the outs.