Justin Theroux appeared to be absolutely buoyant at dinner.

The screenwriter-and-actor recently became engaged to actress Jennifer Aniston.

Justin grabbed a meal with three of his friends in New York City at The Smile Monday Night.

The name of the restaurant was apt, as Justin was grinning cheerfully throughout.

"[He was] beaming all night," a source told People magazine.

Justin and his buddies engaged in delightful conversation over salads, trout and chicken.

Apparently everyone was aware of just how happy Justin was that evening.

"Justin was laughing so loud the whole restaurant could hear him. [They were] obviously having a great time," the source detailed.

Later on in the evening, the group raised their glasses and toasted to one another.

"Justin looked like the happiest guy in the world," the source said.

Jennifer, 43, and Justin have been dating for around 15 months.

The couple became engaged on Justin's 41st birthday August 10.