One look at the huge diamond on her hand – held up for the world to see by Guy – was enough.
The couple looked on top of the world as they stepped out for a bite to eat in London.
There's no word on when they're planning to tie the knot, but it's likely to be after they welcome their new baby.
Jacqui, 30, is about six or seven months pregnant with the couple's second child.
They are already parents to one-year-old Rafael.
He was born in September 2011, but his name was kept under wraps until July this year, when the couple revealed they were going to add to their family again.
Jacqui confirmed the little one's moniker when she attended the Dark Knight Rises premiere with her famous other half.
She told reporters the baby is lavished with attention by his big brothers, Rocco, 11 and six-year-old David – Guy's children from his relationship with ex-wife Madonna.
"The two big boys, they absolutely dote on Rafael. They're always dancing with him and wanting to play with him," she said.
Guy split with Madonna in 2008 after eight years together. He wed the pop star in 200 at Skibo Castle in Scotland.
The director said he was happy during his time with the Queen of Pop.
"I enjoyed my first marriage. It's definitely not something I regret. The experience was ultimately very positive," he said.
In December 2008 Madonna's spokeswoman announced that the star had agreed to a divorce settlement with Guy, which was reportedly between £50million and £60million.
Sherlock Holmes director Guy started dating Jacqui in April 2010, taking her on nights out at his Mayfair pub The Punch Bowl.
They moved in together at the start of 2011, with Jacqui telling Tatler magazine: "I’m living with Guy in Marylebone. I don’t think there was really an official moment – no huge conversation or anything strange."
"We just wanted to spend time together and I was there all the time and evenings after work, so it just kind of happened."
There were also clues back then to the couple's plans to start a family.
"I've known since I was very little that I want to be a mummy and I want to have kids," said the part-time model, who hails from Southend, Essex.