In Google's answer it is said:
"If she only ever sees you as someone who is desperate for her, it doesn't give her much to desire about you, does it?"
I don't believe that this is the main point. Love is unexplainable, you may love someone even if... However, there is another problem with nagging the person about how much you love her: it demonstrates precisely the opposite of what it says. 'Love' of the necessary kind, is concerned with the well-being of the person. While 'need' is concerned with self-desires. If someone 'needs' you, if someone is more concerned about mantaining you in the relation than about what you truly want, then that person is showing that she is blind to you. She lives concentrated on her/his sole whishes and prospects.
The hidden argument runs: you make me happy, therefore you must stay with me, even if you don't want it now. If you go, I'll be miserable. Whereas, true love would say: I want you to be happy, do whatever you feel you must do, I will be always by your side, near or far, supporting you. This is unselfishness of the true kind. Holding on to love when the other partner doesn't feel the same is putting a bolt on to him/her. It is the best expression of saying 'I don't love you' even if by repeating to exhaustion the contrary. And without love no relationship can hold.
True love is very difficult, and implies very difficult decisions sometimes. We associate love with pleasure. Love tends to bring pleasure in the long run, but always as a result. If you are searching for comfort and safety, don't be deluded, that is not love. Love is 'the other'.