Jun 7, 2011 08:45 GMT  ·  By

Jennifer Aniston and Justin Theroux are officially a couple, having made their romance public at Sunday’s MTV Movie Awards 2011. They could hardly leave each other’s side and were constantly kissing, a new report says.

The two reportedly started dating some weeks ago, having first met on the set of “Wanderlust.” So far, they’ve kept their romance a secret, perhaps in a bid to avoid media attention – which they got nevertheless.

At the MTV Movie Awards, Jennifer and Justin came together and, even though they did not pose for pictures on the red carpet as a couple, their behavior backstage left little room to doubt the true nature of their relationship, Us Magazine writes.

After the awards show, at the A-list party, the two really made no effort to hide their feelings for each other – and they are definitely in love, the report says, citing unnamed eyewitnesses.

“Chatting with director Brett Ratner, Aniston, 42, and Theroux, 39, were unabashed with each other. She adjusted his tie, and he gave her a sweet kiss, sweetly rubbing her cheek,” the mag writes.

“Wearing a black dress with a short leather jacket, she smiled ear-to-ear and leaned into her man, who rubbed her neck. As they greeted the night’s host (and rumored one-time Aniston fling) Jason Sudeikis, a bevy of Hollywood agents and writers plus other celebs, the duo remained at one another’s side,” adds Us.

This Sunday’s ceremony also marks the first time that Justin and Jennifer are pictured together: a series of shots taken at the party have emerged online, and you can see one of the pics attached to this article.

“While Aniston chatted animatedly with other guests (including Pattinson, 24), Theroux looked on adoringly, and they exchanged kisses throughout the night,” US further writes.

As they were making their way to the exit when the party was over, there came even more proof of the romance, as Justin grabbed Jennifer’s backside and “stole another kiss.”

An unnamed source swears to the magazine that the two lovers seem to have perfect chemistry together, while it’s clear that Aniston “has never seemed happier.”