I try to remember the following quote when I'm faced with an honesty conundrum:
"A truth told with bad intent, beats all the lies one can invent" - William Blake
Your intent is the key. Under normal circumstances I'm skeptical of "tough love" - although certain circumstances will demand it. Search your feelings for the right approach - and timing is everything! Brutal honesty can often be avoided, to be replaced with a compassionate honesty at a different time under different circumstances.
Obviously lying should be avoided but "white lies" have their place