That largely depends on the individuals involved. I am in a relationship of absolute honesty but I can take it - so can my boyfriend.
I think a good example would be how some women have intense issues with their boyfriend or husband being around attractive female coworkers, or talking about past lovers, or admitting that someone other than them is attractive. To me this is utter silliness. I know about all my boyfriend's previous lovers, as I was interested enough to ask - interested but in no way jealous. I am not threatened by the past. I know if any of them were serious contenders for his heart he'd be with them right now, not me. Not all women are so rational... in fact a great deal are pretty cuckoo on the subject.
As far as white lies.... "No, that doesn't make you look fat" is always a great one.... and are sometimes necessary in all relationships, romantic or not, to spare feelings or not start a fight.