The first question:
Why is love so painful?
Love is painful because it creates the way for bliss. Love is painful because it transforms; love is mutation. Each transformation is going to be painful because the old has to be left for the new. The old is familiar, secure, safe, the new is absolutely unknown. You will be moving in an uncharted ocean. You cannot use your mind with the new; with the old, the mind is skillful. The mind can function only with the old; with the new, the mind is utterly useless.
Hence, fear arises, and leaving the old, comfortable, safe world, the world of convenience, pain arises. It is the same pain that the child feels when he comes out of the womb of the mother. It is the same pain that the bird feels when he comes out of the egg. It is the same pain that the bird will feel when he will try for the first time to be on the wing.
The fear of the unknown, and the security of the known, the insecurity of the unknown, the unpredictability of the unknown, makes one very much frightened.
And because the transformation is going to be from the self towards a state of no-self, agony is very deep. But you Cannot have ecstasy without going through agony. If the gold wants to be purified, it has to pass through fire.
Love is fire.
It is because of the pain of love, millions of people live a loveless life. They too suffer, and their suffering is futile. To suffer in love is not to suffer in vain. To suffer in love is creative; it takes you to higher levels of consciousness. To suffer without love is utterly a waste; it leads you nowhere, it keeps you moving in the same vicious circle.
The man who is without love is narcissistic, he is closed. He knows only himself. And how much can he know himself if he has not known the other, because only the other can function as a mirror? You will never know yourself without knowing the other. Love is very fundamental for self-knowledge too. The person who has not known the other in deep love, in intense passion, in utter ecstasy, will not be able to know who he is, because he will not have the mirror to see his own reflection.
Relationship is a mirror, and the purer the love is, the higher the love is, the better the mirror, the cleaner the mirror. But the higher love needs that you should be open. The higher love needs you to be vulnerable. You have to drop your armor; that is painful. You have not to be constantly on guard. You have to drop the calculating mind. You have to risk. You have to live dangerously. The other can hurt you; that is the fear in being vulnerable. The other can reject you; that is the fear in being in love.