Thats a kind of lie we see very often.
It s not cause they ask the truth that they want to hear it what often they mean when they ask for the truth is tell me something that will comfort me or make me happy.

Of course only lie wouldnt be good either it s all about balance.
After all one cannot be happy whitout being sad sometime.
Some ppl might say i know or i am sad very often yet i aint happy but ask yourself 1 question are you sad or depressed ?