Seen, by an Upper East Sider: Chelsea Clinton, Starbucks, East 66th Street and Third, 3 p.m. with her rumored fiancé, Goldman Sachs broheim Marc Mezvinsky. “She looks very thin and pale,” our tipster observes, and “not exactly ecstatic. How come she’s not working in the middle of the day?” Interesting! Was Chelsea merely playing hooky from Avenue Capital, or is she the recession’s latest victim?