Maybe it's not surprising that women seem, on the surface, often superficial and very short-term in their emotions, but very intense with them on a day to day level.
Hint. Think biology, think 28 days.
At the begining you have the possibility of something life-changing happening to you. You can put your whole heart and soul into that possibility. But if nothing happens - at the end it's just discarded, thrown away, and it doesn't really matter becasue you are all ready to start a new cycle of possibilities. You have done the same thing with love.