I have to agree with the previous posters. Try to remember every time this has happened to you and try to find a pattern. It might be hard because sometimes we think that nothings wrong with our game. Maybe a more detailed post of the last 2 interactions you had this happen, and someone can give advice and breakdown your game more.
All I can think of is either you ATTRACTED them, but not ENOUGH. In this case like previously stated, you can use push/pull and not be so available to them.
Or you built too much comfort when they were only mildly attracted!!...
Were you in a sexual relationship with these girls? or just hooking up? ... Maybe that could be it??.....More info would do wonders...This is an interesting post!!