Witaj Mayex- na Twoje pytanie znalazłem odpowiedź w książce CAMBRIDGE- "English Grammar in Use"- Raymonda Murphy w Unit 41C, strona 82,

-I wish I could (do something)= I regret that I cannot do it :
1-I'm sorry I have to go. I wish I could stay longer. (but I can't)
2-I've met that man before. I wish I could remember his name. (but I can't)

-I wish I could have (done something)= I regret that I could not do it :
1-I hear the party was great. I wish I could have gone. (but I couldn't go)
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Podane przykłady przepisałem z książki jw.

A w związku z zapytaniem: I wish I could have trusted you. ( but I couldn't trust you)

Pozdrawiam- jkp