The LA-based actress – on bombshell form in a ultra-mini Valentino silver shimmering dress and Alexander McQueen blazer – and Scottish hunk Gerard gave a tactile display on the red carpet, further fuelling reports they are romantically involved.
But, despite declaring her love for her hunky co-star, the Hollywood beauty said the couple's compatibility on-screen was the "script's fault."
Playing down rumours of a romance with the "funny and handsome" star, Jen said: "I love my Gerry. We just lucked out – director fantastic, Gerry fantastic, our crew, New York – you just can't go wrong."
And for his part, Gerard was equally appreciative of the 41-year-old actress.
He raved about the couple's "perfect chemistry", adding: "The best thing about this movie is that the two of us got to be together."
"I literally became a member of her family while shooting this movie. I even went to Mexico to see her on her birthday during a day off. It was not a chemistry we had to work at."
In the comedy, Gerard stars as a down-on-his luck bounty hunter who is hired to retrieve his bail-jumping ex-wife Nicole, played by Jennifer.
It is released in the US on March 19, hitting silver screens in the UK just under a month later, on April 16.