we can also use would have + past participle to talk about something you wanted to do but didn’t. This is very similar to the third conditional, but we don’t need an ‘if clause’.
-
I would have gone to the party, but I was really busy.
(= I wanted to go to the party, but I didn’t because I was busy. If I hadn’t been so busy, I would have gone to the party.) -
I would have called you, but I didn’t know your number.
(= I wanted to call you but I didn’t know your number, so I didn’t call you.)