I don't know that I've ever mused about this subject explicitly. How odd.
It's the most powerful, most unknowable, most dangerous human state. Love brings life. Love can kill. We are at our weakest and our strongest when we surrender to its lure. We should be on guard against all the trips and traps that lie down this path: that we can ever know what it is; that we can master it, rather than be mastered by it; that it is nothing more than a feeling; that the exquisite pain and promise are not always one and the same thing.
To love is to allow oneself the privilege of being as fragile as spin glass. We take the risk of stripping ourselves bare before another, giving them free reign in our lives. We can have no secrets, no walled-off areas, no restrictions. Herein lies both the joy and the gravest danger. The hole in our hearts when a loved-one leaves, or passes is the price we pay for allowing ourselves to be fully human.
Yet, all these words are nothing but sounds, meaningless in the face of the reality that is love as it is live out between two people. One can say so much, yet it all falls away in the silence that can bond two people. There is no "reason" for love; there is no explanation, no logic, no QED. It just is. If it's real, it never ends. Nothing - certainly not death, let alone physical separation, or such paltry emotions as anger, betrayal, resentment - can stop it from still sitting there, bleeding its life into our lives, keeping us going form one moment to the next when all we wish to do is stop the pain. We deny the pain as the lie to protect ourselves from the reality that the pain, like the love that is its source, is unquenchable. To live that pain is to embrace not the final word, but certainly the most impossible part of love.
Yet, there is more to love than this. The danger it poses - the threat to our own sense of ourselves, our equanimity, to our very lives - is every bit as real as the joy that comes from those fleeting eternal moments. To love is to live under the constant threat that it will ask of us more than we are prepared to give. To love is to live with the threat of change - real change - hanging over us.
Surrender is the only real option. Whether we stand before the throne of God, or looking in the eye of the one person who knows us better than we know ourselves, love steals choice from us, leaving us with only one recourse. There aren't enough tears of joy in the world for that moment, when we realize that, regardless of all our flaws, the pain, the pettiness and disappointment - not only who we are, but who we can be, is good enough.