The origins of 'love' as a score lie in the figure zero's resemblance to an egg. In sport, it's common to refer to a nil or nought score as a duck or goose egg, and the French word for egg is l'oeuf - the pronunciation of which isn't too far removed from the English 'love'.
There is another theory. In Dutch and Flemish, the word ‘lof’ means honour, so in the most sporting context, anyone struggling to score is still playing for honour.
