[Morsul the Dark]

This may sound silly I do however believe there may be some potential in this theory

I Understand Besides Arwen only one elf loved a mortal man however

Dwarves and elves certainly got along once upon a time and as we see with gimli dwarves are prone to loving elf women

and seeing not set source for hobbit perhaps they were a breed born of dwarves and elves they are afterall elf like in appearance and dwarflike in hight...

I understand this is a farfetched Idea I however have always thought this to be the answer