Attraction
How do we know that we desire someone, or that they desire us?
Are we reading the body language correctly? Maybe we're making assumptions about other people's feelings. The thing to do here is to communicate clearly with the other person what you'd like, and listen very carefully to what they say they'd like.
Clear, respectful communication is essential in intimate matters. If the other person avoids the point, if you begin to feel that they're not to be trusted, or if you feel that they don't understand or respect what you're asking, maybe you'd better look elsewhere, or come and talk things over with a counsellor.