To me, there are all kinds and forms of love. There is not just one definition.

How can someone not to believe in it? That's the only thing I actually believe in! :)

In my humble opinion, love is the feeling that could not appear suddenly, this is the thing that grew year by year, and it certainly exist.

yes, why not. 

like the lyric said'sometimes it last in love, but sometimes it hurts instead'. I believe that I broke up with the Mr. Wrong, and now I have chance to find my Mr. Right.

I agree with GGM comment with love.  There is not just one definition.  You may  hold various   significance in different way, different time and different subjects . It is very hard to define love in simple words so be cautious to "I love you" because it takes diverse implications.