No, I’m not going to try to answer that one tonight. For an earlier attempt see here.
However, a really good place to start (or end!) could be this ancient Gaelic poem, translated here:
What is Love?
A love much-enduring through a year is my love,
It is grief in the heart,
It is stretching of strength beyond its bounds,
It is the four quarters of the world,
It is the highest height of heaven,
It is breaking of the neck,
It is battle with a spectre,
it is drowning with water,
It is a race against heaven,
It is champion-deeds beneath the sea,
It is wooing the echo
So is my love, and my passion
And my devotion to her to whom I gave them.