"I had a piece missing," the Grammy Award winning singer, 26, tells PEOPLE. "I thought, "Who am I going to have those special moments with?' I needed some arms around me."
A self-described "hopeless romantic," the Welsh-born singer-songwriter found that comfort in rugby star Michael Phillips, whom she began dating in September 2009.
"The story is yet to be finalized," she says, "but it seems like a happy ending."
Listen to the track here:
And Duffy is channeling that upbeat spirit on her new album, Endlessly, due out Dec. 7, on songs like the disco soul-inspired "My Boy" (listen to it here) and the sassy dance track "Well, Well, Well," which, she says, "is about me letting my hair down and being young and mischievous."
Duffy – whose full name is Aimee Ann Duffy – is able to get away with being mischievous because, as she tells it, "people find it hard to be nasty to [my] dimples!"