What is LOVE?

"Love is the master key that opens the gates of happiness." "Love makes your soul crawl out from its hiding place." "Love is everything it's cracked up to be. That's why people are so cynical about it... It really is worth fighting for, risking everything for. And the trouble is, if you don't risk everything, you risk even more."

The above are quotations of what love is. Each has differing perceptions of what love is. I used to define love as a giving act that requires no returns and creates satisfaction to the receiving party. To love, without expectations of being loved - I told myself that the motto of loving unconditionally should the way I lead my life.

I questioned my motto today. Afterall, my ex just got attached. I sent her my congrats. But deep down inside, the feeling of being delighted to celebrate the joyous occasion wasn't how I expected it to be. There's a host of reasons that could contribute to this.
(i) I lost the feeling of how love is.
(ii) I grew tired and exhausted of loving.
(iii) There's no more love btween me and my ex.
(iv) My definition of love should be changed.

I asked myself which of the reasons it could be. Or maybe it's just all of the above.