"They had a great time in New York," a source close to the singer tells PEOPLE of her weekend with Swiss executive Frédéric Thiébaud. "They did tons of Christmas shopping and ate out at places like Nobu and Serafina. She loves taking in the sights New York has to offer during the holidays. It's her favorite time of year there."
And what a difference two years makes.
The Christmas trip is an annual one for Twain, who has traditionally gone with a group of pals. But two years ago, just a few months after Twain's husband of 14 years, music producer Robert "Mutt" Lange left her for another woman, Thiébaud joined her on her N.Y.C. weekend.
At the time, a source close to Twain told PEOPLE, "They're friends. There's nothing more to it – at this time."
This year, the newly engaged couple was joined this year by Twain's sister and a few friends.
Twain, 45 and Thiébaud, 40, grew close in May 2008 after both of their marriages broke up amid an alleged affair between Lange and Thiébaud's then-wife, Marie-Anne, a longtime secretary and manager of the couple’s chateau in Switzerland.