Latsis proposed on Wednesday, the day Hilton, 24, returned home to Los Angeles after a three-week trip to Europe, where she promoted her thriller House of Wax and her new fragrance.
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"I'm very in love – he's the one," Hilton told PEOPLE earlier this month. "I want to have kids in the next two years, because I know that completes your life."
No date has been set for the wedding. This will be the first marriage for both.