Is there a term for "the one that got away"?

Question

I'm thinking of something like 失恋対象 or 失恋相手, except 1) I just made those up off the top of my head, and 2) on the off-chance they're real words, they don't really capture the essence of "the one that got away".

Answer 1

The most versatile (and thus the most often-used) terms would be:

「逃{に}がした魚{さかな}」 and 「逃げた魚」

both of which practically mean the same thing though they take different grammatical forms.

「魚」 in these expressions can refer to a prospective love partner, business opportunity, etc. It can refer to anything you once almost had.

「魚」 does not need to refer to a fish unless you actualy are talking about fishing. People do tend to brag about the size of the fish they almost caught in fishing, which is why we often say the whole sentence:

「逃がした魚は大きい。」

Again, this sentence is often used about things/people that are completely non-fish-related. "The one I let go was huge."

IMHO, 「失恋対象{しつれんたいしょう}」 and 「失恋相手{しつれんあいて}」 look/sound pretty stiff and overly-serious.