"Albert proposed to Lisa on Christmas Eve," a representative told People.
Niemi, 57, and DePrisco, 58, met at a birthday party for a mutual friend and have been dating for a year and a half.
About a year after her husband passed away, Niemi told People she would be open to getting married again.
"I would love companionship love. Absolutely. I hope I'm not one of these women who never want to have another relationship," she said. "But who knows, that's another bridge I'll cross when I come to it. I may get there and go, I don't know. But I like to think that I can."