After attending Anna Wintour and Sarah Jessica Parker’s fund-raiser for President Obama on Thursday night, Andy Cohen headed to the Hamptons to start a summer fling. Spies saw Bravo’s “Watch What Happens Live” host over the weekend on a secluded East Hampton beach, looking cozy with a mystery man. “Andy and another guy were lying near each other. They were kissing, and then they were lying with their legs on top of each other,” said a source. A rep for Cohen — who has a house in Sag Harbor — had no comment as to who his mystery man is. “On his show, Andy goes into every little detail of his guests’ lives,” said a source, “but when it comes to his personal life, he’s very private.”