Most of the scenes are real. Long gone are the days where such scenes were considered a taboo or filmed with flowers or some objects coming in front of the actors to mask their kiss.
Thank god Pahlaj Nihalani doesn't have a problem with these.
Many actors and actresses are unmarried. Those that are married have an understanding with their wives/husbands that Bollywood is their source of income and they can't refuse a movie for such a scene.
If you remember, Saif Ali Khan and Kareena Kapoor had mutually agreed to not shoot any intimate scenes with other actors. But they soon dropped it, because they realised that all of this is a part-and-parcel of their lives.