Mary-Kate Olsen is dating the half-brother of former French President Nicolas Sarkozy. The actress-turned-designer is understood to have been romancing financial businessman Olivier Sarkozy for around a month. According to New York Post, the 25-year-old star and 42-year-old professional are \"head over heels\" in love. They apparently spent Memorial Day weekend in the Hamptons, New York. The pair were seen enjoying the break together, but no details of where they stayed or what they did for the majority of their time there are known. Mary-Kate has been single since early 2010, when her romance with artist Nate Lowman ended. The pair were together for around two years and even sparked marriage rumours after she was seen wearing a ring on her engagement finger. At the time of their split, it was claimed Mary-Kate was looking for more \"substance\" in a relationship. She has previously dated Greek shipping heir Stavros Niarchos III and Maxwell Snow. Neither of the couple\'s representatives has commented on the report.