Have you ever said to a girlfriend, "He's such a great guy; but when I'm with him, I don't feel any passion." Or, "She's really pretty but she just doesn't turn me on." Or, "I meet so many boring men, why can't I meet one who excites me?"
Do you seldom meet somebody you feel an immediate chemistry? If your regular dating experience is that you rarely meet someone who sexually attracts and interests you - it could be because you are dating the wrong type of man (or woman) to fit your needs.