The romance between Leighton Meester and “Mac guy” Justin Long is heating up. The pair are currently in the city, where Meester is filming “Gossip Girl.” A source told us, “Justin has a place on the Lower East Side, and they have been spending a lot of time together.” In May, the pair were spotted sharing a romantic dinner in LA before leaving restaurant La Poubelle holding hands. Long split with Drew Barrymore last year. Meester played Long’s girlfriend who leaves him at the beginning of the 2010 movie “Going the Distance.” Their reps didn’t get back to us.