I get why I girl would not to propose. It is permissable though for both a guy and girl to speak to each other about the issue though. A proposal (from the man's side) means that the girl is now taken not for anybody else to approach. So I understand why a woman would prefer a man to do the proposal. At the same time, approaching a person with questions (direct or indirect) is the same if it comes from a man or a woman in my personal opinion. Well, rarely happens that a sister approaches a brother, but there is nothing wrong with it and is not a sign of desperateness. If anything, it's a sign of decisiveness.