In order to maintain a good, healthy relationship with another person, there are many considerations. Some are more important than others. Personally, I think that always telling the truth is the most important aspect of any relationship between people. This is because lies hurt people's feelings, no matter how innocent the lie may seem. Telling the truth is better for everyone involved, for, if you cannot trust someone it is difficult to get close to them emotionally.
First, telling the truth is very important because lies hurt people's feelings, no matter how innocent the lie might seem to be. On the other hand, many people believe that telling lies is not bad because everyone tells a lie at least once in their life. For instance, if you lie to your best friend and say that you didn't eat his cookie, it does not seem very hurtful. However, if your friend finds out you lied to him, it can make him sad that you didn't tell him the truth. More serious lies only hurt others more and cause tension in the relationship.
In addition, telling someone the truth is better for everyone involved. Conversely, some people think that, sometimes, lies can help people. For example, if you tell your parents that you don't know who ate their pie when actually you saw your brother eating it, you may think you are helping your brother by keeping him out of trouble and helping your parents by making sure they are not angry about their pie. But if your parents found out you knew that your brother ate their pie, your parents would be even angrier and they would likely punish both you and your brother. Again, more serious lies can be even more damaging to one or more of the parties involved. As helpful as you may think you are, any lie can be harmful.
Lastly, if you do not trust someone it is difficult to get close to them emotionally. A lot of people think that if you know that someone lies all the time, you can simply overlook it. But when you're not sure if what someone says is true, you start to doubt if anything they say is true. When you can't trust a person to tell you what they really think, it is easy to withdraw emotionally from them so you don't get hurt. When one person closes himself off emotionally, the relationship can be difficult to sustain and even more difficult to develop further.
Ultimately, telling the truth is the most important consideration in any relationship between people. For, it is important to keep in mind how a lie - no matter how small - will make a person feel, if the lie will make things better or worse for everyone involved and if the lie will make it more difficult for the people to be emotionally close. In my experience, telling a lie has always hurt one party's feelings, made a situation worse, or made it difficult to connect emotionally. Thus, it is critical to always tell the truth in a relationship.