What is Love?

My French teacher, who was Polish, told us that the French didn't distinguish between the meaning of the words 'like' and 'love'. I bablefished the two words from English to French and came up with the words, 'comme' and 'amour'.
Maybe the language had changed from the 1960's or maybe my French teacher wasn't very good.
Whilst at it I bablefished the languages French, Dutch, German, Greek, Italian, Portuguese, Russian and Spanish. Each language had different words for 'love' and 'like'. Incidently they all had the same word for 'infatuation'.
So what is love?
My first thought was that it was an extreme form of likeing, but then so is infatuation. I'm sure most people would agree they are quite different.
So 'love' implies some sort of durability. This differentiates it from 'infatuation'. One additional unpleasant fact known about the subject of infatuation and the feelings implode.
But when does 'like' become 'love'?
Is it at an arbitrary point on a scale of 'liking' from 1 to 10. Let's say 7. So if you like someone more than 7 does it then become 'love'?
As a relationship progresses, a kind of emotional 'credit' is established. This credit is what carries the relationship through times of difficulties, or allows us to tolerate the almost inevitable flaws found in ones partners. A long history of credit will allow us to put up with a loved ones behavior going into 'emotional debit', but there comes a point when losses have to be cut.

"You'll know it when you feel it."
Maybe you will, but I'm uncomfortable with concepts I can't define.
I needed more research.

Plato started the ball rolling. He reckoned we only love the best bits of someone. Hmmm. This pre-supposes we know what love is and goes on a different tack. Sorry Plato, you're not much help.

At the turn of the first millennium, the roman writer Ovid, described love as a hunt, the lover and beloved are "shy predator and wily prey" and the nature of their love was "conquest."
Ovid......obviously a bloke then.

In 1822 the French writer Stendhal. Invents an analogy of the process of falling in love as being like a journey from Bologna to Rome. The analogy is entirely pointless so I'll cut to the chase.

Phases;-

1. Attraction. ( The 'phwar' stage )
2. Acknowlegement of return of affection. (I was looking back, to see if I she was looking back, to see if I was looking back at her)
3. Hope. ( envisioning gaining the love of the loved one)
4. Delight. (exulting, in the overrating, of the merit, of ones beloved)

Not much of a definition but some good points about falling in love are made.

Turn of the last century and the pioneer sexologist Havelock Ellis comes up with the equation.

Love = Sex + Friendship.

You may not agree, but it is refreshingly simple.

For a more complex and accurate appraisal, take a look at Triangular Theory of Love.

To me, it has to be more than Sex + Love, it has to involve some kind of connection.
So what do I mean by connection?
I don't know, maybe that's just another word for love. Which brings us back to,

You'll know it when you feel it.