Just as food for thought - why is a work situation different in this? Why might you think that I'd take criticism well in one context and not another? (I use myself as an example because, well, I do deal with you in both contexts, and would hate to think that you're withholding criticism in either.)

Also, y'know, sometime I'd rather lose the face and keep the friend. It's ok to be wrong. It's not so ok to never know if your comments mean that you wish I'd do something differently, or that you're actually ok with things.