Is this past perfect conditional tense. I understand it refers to unreal situation in the past. Nothing can make it otherwise.
Any help appreciated as going around in circles. http://www.usingenglish.com/forum/im..._img/icon9.gif
No, this is not conditional.
'should' combines with the perfect infinitive to form 'should have' + past participle when we want to talk about past events that did not happen, but should have happened.
It is not that the past situation is 'unreal' or 'improbable' etc.
It's more like kicking yourself for not taking advice, someone else's ...or your own!
"I knew I shouldn't have trusted him!"
Certainly, 'things would have turned out differently if ...if I hadn't blindly trusted him".