snip:
Shortly after takeoff, Varnier nodded off, leaning his head on Tsikhiseli. A stewardess came over to their row. “The purser wants you to stop that,” she said.
“I opened my eyes and was, like, ‘Stop what?’ ” Varnier recalled the other day.
“The touching and the kissing,” the stewardess said, before walking away.
Tsikhiseli and Varnier were taken aback. “He would rest his head on my shoulder or the other way around. We’d kiss—not kiss kiss, just mwah,” Tsikhiseli recalled, making a smacking sound.
snip:
Maybe an hour later, the purser approached Tsikhiseli and said that the captain wanted to talk to him. Tsikhiseli went up to the galley and gave the captain his business card. The captain told Tsikhiseli that if they didn’t stop arguing with the crew he would indeed divert the plane. “I want you to go back to your seat and behave the rest of the flight, and we’ll see you in New York,” he said. Tsikhiseli returned to coach.
Tim Wagner, a spokesman for American, said that the stewardess’s injunction to the men was reasonable, and would have been made whether the couple was gay or straight. “Our passengers need to recognize that they are in an environment with all ages, backgrounds, creeds, and races. We have an obligation to make as many of them feel as comfortable as possible,” he said. (He added, “Our understanding is that the level of affection was more than a quick peck on the cheek.”) But a customer-service representative named Terri, reached last week on the telephone, offered the opinion that kissing on airplanes is indeed permissible. “Oh, yeah! Sure. I’ve seen couples who are on honeymoons,” she said. “They just don’t want you to go into the bathroom together.”
http://www.newyorker.com/talk/content/articles/060925ta_talk_collinsThere's a little more about the story and the lying purser at the link, but basically it's okay for straight couples to be affectionate, but not gay couples.