Learn English – One word for a watch enthusiast / watch lover

The National Association of Watch and Clock Collectors does not use any specific word for it, which in my world gives a strong indication that there is no consensus on a single word.¹

Horologist has been mentioned, and most horologists are probably clock enthusiast. All clock enthusiasts are however not horologists:

: a person skilled in the practice or theory of horology

: a maker of clocks or watches

Horology again is defined as

: the science of measuring time

: the art of making instruments for indicating time

Depending on what you need the word for, you might be able to use Horologist in some cases, but definitely not all.

EDIT:

That being said, John Clifford mentioned horophile in the comments, and even though I wouldn't expect most people to know this word, it seems to be exactly what you are looking for. I did some research, and it does not exist in the merriam-webster dictionary, but there are a few online dictionaries who do define it as:

a person who has an obsession with timekeeping devices

There even is a blog by a clock enthusiast, called The Horophile

The lack of this expression's mainstream usage is probably due to the limited numbers of horophiles, and/or maybe even it's phonetic similarity to someone who is into prostitutes.

¹ _{In comparison, the national association for stamp collectors are called The American Philatelic Society, and a stamp collector/enthusiast is called a philatelist.}