This is so true, you should always tell the truth, and like you said it is the way you say things, and how it comes out of the mouth. The bible says you can speak life or damnation on your self by what you say. These are some things that comes from telling the truth.
1. show respect
2. showing them you care by being honest
3. building a relationship with that person
then put in certain situations, you may be afraid to be honest. Yet the truth may actually be rewarding. For example, maybe you had a troubled childhood, and as a result, you are not close to your mother or father, but your fear of looking bad prevented you from sharing your childhood experiences with your significant other. Now say a big holiday is approaching, like Thanksgiving, and your mate asks you to invite your immediate family. If you made up a lie to avoid telling your girlfriend the real reason you do not want to invite your parents, the fabrication may cause your girlfriend to believe she is the reason you do not want to invite your family. Part of the reason telling the truth is so difficult is because it involves telling someone something they may not want to hear, according to Truth About Deception, an online relationship resource. Even though telling your truth may be uncomfortable, it could possibly strengthen your relation
Author Ruth Ashby