Tough love has a place in friendships and romantic relationships. It is a way of establishing boundaries in the relationship. It is a way of saying that I love you but I cannot continue to be a part of what you are doing. Tough love is used for out of control behavior such as drug abuse. It is not used as a way of manipulating someone's behavior.
Tough love is necessary in all friendships and romantic relationships. If you really care about someone you will be willing to tell them things they do not want to hear if it will benefit them in the long run. Not telling them the truth is worse because you are allowing them to hurt themselves.
My first inclination was to say no, but I do believe that tough love has a place in friendships. Sometimes your friends can be in denial about something and they really do need a slap in the face (metaphorically, not literally) to bring them back to reality. I wouldn't say the same for romantic relationships, though. You have to be gentler with lovers.
In both a friendship and romantic relationship you have someone in your life that you care about and it pains you to see them acting in a way that is self destructive, I think sometime the only way to get to a person is if their partner or friend directly lays it out on the table that there is a problem.