It seems that throughout his last two incarnations the Doctor's really been more tolerant with his companion's boyfriends. The Ninth and Mickey got off to a rocky start but by the tenth incarnation they were more or less good friends (Although Mickey was still jealous of him in "Girl in the Fireplace"). Then of course there was Adam. Perhaps this time the Doctor is becoming less romantically attached to his companions after the recent "hearts" break; as for the kiss in the trailer, that could be a case of something that it doesn't appear to be, much like pretty much every Doctor/Rose kiss. Their first kiss he was drawing the energy from her, second she was under Cassandra's control, and the last was his clone! Come to think of it the only really romantic kiss he's had is with Madame pompadour!