I wish I could have p.p/had p.p

Question

Albate I think this issue is pertaining to the standard or slang English, Still I want to ensure if it's related to that or not.

Since I came across many times in movies and some everyday english talks they use the main clause of the 3rd conditional as the next part of a wish clause. The following example could illustrate much easier though.

i. I wish I could've gone there.

ii. I wish I had gone there.

Regarding the example, I need to know:

1.What's the difference between two in terms of meaning?

2.Is this variation regarded to the issue of standard/slang English or they totally differ from each other in terms of grammar?

Answer 1

Both are normal grammatical English, not slang.

A key difference is that "could have" often emphasizes a passive lack of opportunity, while "had" sometimes implies an active decision.

I wish I could have gone to your birthday party.

I could not. Why not? For unstated reasons: it was not possible, I could not have gone, I wish the universe had been otherwise, I wish I could have gone.

I wish I had gone to your birthday party.

I did not go. Why not? Perhaps due to an unstated choice: I chose not to go, I wish that I personally had made a different choice, I wish I had gone.

Note that "had gone" does not unambiguously claim choice and responsibility -- however "could have gone" clearly denies choice and responsibility.