Have you ever been in love? Horrible isn't it? It makes you so vulnerable and unguarded. It opens your chest and it opens up your heart and it means that someone can get inside you and mess you up. You build up all these defenses, you build up a whole suit of armor, so that nothing can hurt you.
Then one stupid person, no different from any other stupid person, wanders into your stupid life...You give them a piece of you, some part of you that you unconciously give in to... They didn't ask for it. They did something dumb one day, like kiss you or smile at you or hold you, and then your life isn't yours anymore. And the best part is... you're aware of it. You know that its happening but you just let it in. Let the whole goose-bumping-good-feeling aura take control of you. Hence, the heart is left unguarded, in the hands of another.
Love takes hostages. When it gets inside you and abuses you.... It eats you out and leaves you crying in the darkness, so simple a phrase like 'maybe we should be just friends' turns into a glass splinter working its way into your heart. It hurts. Not just in the imagination. Not just in the mind. It's a soul-hurt, a real gets-inside-you-and-rips-you-apart pain. But this is the part when all things fail.
So don't let it fail you.
We tend to make promises according to our hopes and dreams that we want to hold on to but tend to perform according to our fears. Try not to let that happen too often and embrace whatever you have and never take it for granted. Love fails only when you let it fail.