Interpretations of “〜てよかった”


I had always though “。。。〜てよかった” can both mean “I'm glad that ...” and “I wish
it were that ...” depending on context but I've recently been told that my
understanding is wrong and it can never mean the latter. Yet, I'm fairly
certain I've encountered the form, and continue to encounter the form with
clauses that are clearly counterfactual. The other way out I'm possibly seeing
is that it's a literal past form of “〜ていい” and that it thus means “I could
have ...” such as “ここに来なくてよかった。” also being able to mean “I didn't have to
come here.” opposed to my initial interpretation of “I wish I didn't come
here.”. Is that interpretation more correct or can it, in fact aso mean “I
wish I didn't come here.”?




“I didn't have to come here.” and “I wish I didn't come here.” are essentially
the same interpretation for “ここに来なくてよかった。” You wish you didn't come because
you didn't have to.

* * *

  * ここに来てよかった

always means _I'm glad about my coming here._

  * ここに来なくてよかった

Since ここ suggests the speaker is already "here", s/he cannot be glad about
_not_ coming "here" **now**. So, either (1) the speaker did come and regrets
on it ("I didn't have to come here") or (2) the speaker is glad about not
having been "here" **in the past** ("I'm glad that I didn't come here").

* * *

Another example.

  * 新しいスマホを買わなくてよかった.

By default, it would be understood as _I am glad that I didn't buy the new
smartphone_ (e.g., because the model turned out to be bad in battery
consumption). In this interpretation, the speaker **didn't** buy the phone.

In some contexts, it could mean _I didn't have to buy a new smartphone_ / _I
wish I hadn't bought a new smartphone_. In this case, the speaker **did** buy
the phone. For example, you thought you needed a newer phone to play a new
game, but actually the older model turned out to be enough for the game.
新しいスマホを買わなくて **も** よかった should be more common (lit. It was fine as well if I
didn't buy a new phone).

* * *

In general Xしてよかった tends to be "I am glad ..." whereas Xしなくてよかった is "I wish I
didn't...".

Note that しなくてもよかった is unambiguously "I wish I didn't...".

