The other person is desperate, and desperate people have less power.
To get to the medium, u have to start out equally. It may start with guy asking girl out, but he shouldn't spend so much on her...just a coffee. Next time a dinner. After that, she should pay on the 3rd date. If not, he don't need her. If girl wants the medium, she shouldn't give sex so soon. The longer, the better.
It's easy to get to the medium, but to get there, u lose a lot of people and spend a lot o time a lone.