It's sad that the most glorious of sexual experiences can make us feel guilty, ashamed, embarrassed, and abnormal.
Acting is a really simple job - it's just hard to do. You just have to be that person with their background in that situation. That's all it is. My kids do it all the time when they're dressing up and playing games.
Someone I met years ago explained to me the difference between a personality and an actor, a personality being Eddie Murphy or Roseanne Barr, and an actor being Morgan Freeman and Alfre Woodard or Marlon Brando.