Without Trust there is nothing
The kind of lying that is most deadly is withholding, or keeping back information from someone. A lie is deliberate and conscious behavior that either misrepresents important facts or conceals and withholds them in order to keep them from knowing the truth about certain facets of their partner's past, present, and often, future. Lying in relationships ruins the foundation of trust.
Why do people lie to their significant other? People may lie because it seems easier than telling the truth. People may lie to avoid the unpleasant encounters the truth may lead to. What ever the reasons are for their lies, people need to understand that no good will ever come out of lying. Although they hurt the other person, they also hurt the way others see them. Nobody can trust a liar.
Being lied to affects our thoughts, our feelings, our behavior, and our relationship with the other people in our lives, and our self-respect. After being lied to it is hard to trust the one who lied to us. Gaining back trust is hard to do. When our companions lie to us it we become depressed and feel as if we don't know our loved one. Plus relationships are based on trust and if one is lying to the other the foundation of their relationship is gone. When we are lied to we often find our selves unable to make even the simplest decisions with our partners, because trust has disappeared, and we do not know when or if they are telling the truth.
Relationships will last longer if the couple is 100% honest with each other. Even though the truth may hurt the other, it would hurt worse if they were lied to. People who lie to others are only looking out for themselves so they do not get in trouble. Personally I think that those who lie are heartless only because lying to a loved one is misleading them into thinking better than things really are. Lying in relationships is not fair to the other person.