I don't get this trust discussion. I don't trust myself not to do a mistake, why should I trust somebody else.

Also - while pair programming is great - it does not replace a code review. When you do pair programming you start working on the problem at the same time, you get tiered and annoyed of the problem at the same time. You want to go to lunch break at the same time. All reasons to slip in a sloppy solution and convince each other it is actually ok.

While doing code review you get a fresh perspective on the matter.