We love Jennifer and Justin!

Jennifer Aniston celebrated fiance Justin Theroux's Details magazine cover at a private dinner party on Tuesday night -- and both looked sophisticated as all hell in all black!

During the dinner, the couple posed with the mag's Editor-in-Chief Dan Peres at the event celebrating Justin's August cover.

The 42-year-old Leftovers actor and the 45-year-old former Friends actress dined with Courteney Cox, her fiance Johnny McDaid, Malin Akerman, and Colin Egglesfield at swanky dinner.

In the mag, the hunky actor talked about his high-profile relationship with Aniston, revealing that the duo first bonded over the, "Waldorf grade-schooling they both received."

When talking about dating a woman with mega-watt fame, he said, "It doesn't feel like a hardship, it doesn't feel difficult," The leather-loving actor added, "It can be an annoyance, but it's not the end of the world. You have to center on what its core thing is, which is that you met someone you fell in love with. It's hard to explain. I just find myself wondering, 'What's the big f---ing deal?'"

Looks like they are making it work!