The feeling that you are falling into a pretty dark pit because he is not there to catch you. The feeling you just had your heart ground up like meat. The feeling that there is absolutely no hope for love anymore, at least not for you. The feeling that you will end up a cat lady, knitting sweaters and growing toxic plants with your best and only friend, because together, you are heartbroken.
The boy you love just rejected you, saying, "there is someone else, so....", and you are now heartbroken.
The boy you love just left you for some other girl, probably not even as pretty, leaving you heartbroken and miserable.