Report: Long and Mara dating Actors Kate Mara and Justin Long are reportedly dating. UPI/Kevin Dietsch/Jim Ruymen NEW YORK, June 8 (UPI) -- Hollywood actor Justin Long recently began dating actress Kate Mara, a source close to the new couple told UsMagazine.com. The pair were spotted walking arm in arm in New York last weekend and taking in a performance of the musical "Jesus Christ Superstar" on Broadway last month, the report said. Mara, a former "American Horror Story" co-star, is the 29-year-old sister of Oscar-nominated actress Rooney Mara. Long is the ex-boyfriend of film star Drew Barrymore, who married art consultant Will Kopelman last Saturday, Long's 34th birthday. Long's film credits include "He's Just Not That Into You" and "Going the Distance."