Love can be a potion for immortality or a poisonous drug. Either way, you'll feel great for a while. It'll feel like you're floating, the rush of endorphin will be like that. After a while, you calm down. You see the loved one in a different light then before. You'll want to marry them. Spend an eternity with him. That's how it goes.

Sometimes the person loves you back and you really do strive to be with him forever.

Sometimes that doesn't happen. Sometimes he leaves you with your shattered heart, rotting away on the streets while he falls for someone else.

If the person doesn't recuperate your feelings, you'll die. You'll die spitting at the ground he walks on, ruing the days you loved him. You'll spite him will all your might, but still not manage to stop loving him. Eventually, your misery and bitterness will be too much and your heart will stop beating. But what'll really kill you is the fact that you hate him because you love him.