You cannot game or manipulate your way into genuine interest & desire. It is either there from the start or you are not her type and will never be able to reach that level. Every girl has a type of guy that they have wet dreams over and if you match or come close to that image then you will start in a cheat code position with her. If you are starting from a non-genuine interest starting point then yes, her interest can fade at any given moment because you were never top priority in her mind. Unless you are caught in a rebound situation like I mentioned earlier. Otherwise, she essentially settled for you which means she is going to be open to other options and more critical of you. If you are not her ideal type then she will test you more, make you wait, and try and look for reasons to swap you out when necessary. Otherwise, she will throw Mr. Sunshine softball pitches and give him a pension plan. However, unless you have been "that guy" to a woman, you will have trouble understanding what I am talking about.