How do I get one

The only thing that I don't like is when people, guys or girls, whine about how they have been led on when the other doesn't even know that they were interested.

People are usually lead on because of a confused or unclear goals. Not intentionally. Unless the person clearly enjoys playing and toying with people's feelings. In which case the situation should be obvious in the end. Misunderstandings and interpreting people's feelings the wrong way is what causes most cases of being lead on.