"Jennifer is walking on air. She's madly in love with Nicholas and is the happiest she's ever been. Jen likes to live a relatively modest private life. She knows news of the engagement will make that harder if not impossible. And she is obsessed with her privacy."

The insider added that Jen and Nick spent the festive season at her family home in Lexington, Kentucky - with the actor seeing it as the perfect opportunity to propose.

They explained: "Jennifer is extremely close to her family, When she isn't filming or promoting her movies, she spends a lot of time at her parents' house. All the family had gathered in the living room, enjoying the night before Christmas when Nick asked for everyone's attention and began giving a speech to Jennifer. He stook up and took her hand, helping her to stand up as well. When she was on her feet, he knelt down and pulled the ring out of his pocket and asked her to marry him."

The American Hustle beauty is said to have 'cried and screamed' when being presented with the ring after accepting his proposal.