Amanda Seyfried and Justin Long were “almost inseparable” at Tuesday’s Cinema Society premiere of Seyfried’s film “Lovelace,” about the iconic porn star. “They were hanging out at the after-party at Refinery Rooftop till closing time,” said a spy. “They looked cozy in a corner.” But a source close to Seyfried tells us they’re “just friends.” Also at the fete were Peter Sarsgaard, Sharon Stone, Chris Noth and Hank Azaria, who were joined at the MCM-sponsored bash by Zachary Quinto, designer Zac Posen and Gloria Steinem. Seyfried has previously dated Ryan Phillippe and Dominic Cooper. [For more on the screening, see Page 18.]