What thing is love?

What thing is love? I pray thee, tell.
It is a prickle, it is a sting,
It is a pretty, pretty thing.
It is a fire, it is a coale,
Whose flame creeps in at every hole,
And as my wits can best devise,
Love's darling lies in Ladies' eyes.
(John Bartlet, 1606)

I'vew just been reading someone's blog, it has prompted some thoughts and I want to give expression to these thoughts a moment. I'm always perplexed and a little alarmed by the words "I love you". I find those words hard to say, even to people I do love. The question "Does he love me?" or "Do I love him" - what exactly do these mean? So many agonise over these words. They seem to have something irrevocable about them.

To me, love is not a precipice over which you jump, never to climb back up again. It's not a question of "Has Cupid shot his arrow into me/him/her", but rather, "How many arrows has he shot, what part of the body has been wounded and how virulent is the poison?"

The love I have for my wife is based on different factors: I like her body, the feel of it especially; we have done simple things together, are bringing up a child together, have told each other things, secrets perhaps. She's a good listener. We have one or two interests in common (but a lot not in common.) She's a simple person, I'm more complex and contradictory. I want her to be happy, be active in something she enjoys. She lets me do what I want to do, is quite submissive yet quietly strong.

But many of the same things could be said of my ex-wife. Am I "in love" with her? No. I can say that with certainty. But she has been perhaps my best friend for forty years. Am I "in love" with my present wife? I don't know, I wish I knew what that means, if it's important, as many think it is. She isn't my best friend, I think. We are better suited sexually than my ex and I were, though; yet not ideally. The whole business of love between the sexes is very hard to get clear about. Does anyone have a magic light to throw on the matter?