We've all heard the phrase "speaking the truth in love." The problem is that most of us don't really know what that looks like. So we speak the truth in something else. It might be pride. It may be resentment or bitterness. It could be in judgment. Or maybe we just don't speak at all, thereby avoiding confrontation.
Speaking the truth without the love is just mean. But being silent in the name of love, and allowing the other party to go on deceiving or even destroying themselves isn't any better. It may be the worst perversion of real love.
Love means that sometimes we must confront those we truly care about. Both authenticity and personal concern are needed when dealing with people who are ruining their lives with sin. So if you see someone caught in a sin, ask yourself, "How much do I really love this person?" And then act on the strength of that love.