I have never understood this form of scoring. What is the origin of this score "title".
There seems to be some debate on where the term started.
One common explanation is that it was adapted from the French word l'oeuf (pronounced "luff"), which means egg or zero. In American sports, we often use a similar term of goose egg to refer to a score of zero.
The Oxford Dictionary also believes that the term "Love" could have been adapted from the phrase "to play for love [of the game]". Meaning that, if you have no score then you must be playing for the love of the game because you are obviously not very good.
There are many theories on origin of "love" in tennis few of them are as follows,
Less popular theory uses the Dutch or Flemish word “lof,” meaning “honor.” The idea is that the player with zero points is simply playing for honor—because he or she certainly isn’t playing for a win. Source
Another possibility comes from the Dutch expression iets voor lof doen, which means to do something for praise, implying no monetary stakes. (Cited source: Bondt, Cees de (1993) Heeft yemant lust met bal, of met reket te spelen...? Hilversum: Uitgeverij Verloren p. 10) Source
The origins of the use of "love" comes from the acceptance that, at the start of any match, when scores are at zero, players still have "love for each other". (Cited source: Collynshum, Cirt Frijk (1971) Brikt noordjest tennis ul areven Kreb.: Steken of en lad Verk p. 132) 1st, 2nd
The Oxford English Dictionary suggests that the term might be rooted in the colloquial phrase “for love,” meaning “without stakes being wagered.” This theory reflects the sport’s long history of etiquette and sportsmanship. Source