Most people don't want to readily admit that they do personally lie, mainly because admitting to such, basically reflects poorly upon them. After all, being a liar is essentially admitting that for whatever reason, good or not, mitigated excuse or not, a person has deliberately told a falsehood, in which, the most obvious reason why this is done, is in order to protect oneself from potential scorn or reprimand, as well as doing so in order to make oneself look better than one actually is.
Lying has an awful lot to do with people, simply not wanting to face the consequences of either what they have done, or who and what they really are. Additionally, because lying seems in many instances to be effective, in the sense that the other party does not seem to be aware of the falsehood; it thereupon reinforces itself in the liar's mind that this is indeed an effective tool to be utilized, especially when other avenues appear to be far less inviting.
The other thing about lying is that there are definite material degrees of lying, in which "little white lies" are considered to be socially acceptable by most people; whereas a constructed lie which has catastrophic consequences, usually for someone else to suffer from, of which this lie greatly impacts their life for the worse, is considered to be a lie of real ethical import, as well as a lie that once set in motion, is not something that can ever successfully be taken back, for the deed has been done, forevermore.
So too, it is always discomforting, when someone close to you, lies to someone else about something that is relatively small, knowing that you are quite aware that what they just said is indeed a lie. While some people, might just say, that it was, after all, just a little lie, of no real meaning; that is probably not the right way to think about it. Far better is to think that if someone is willing to lie about something so small, and feel not a tinge of regret or shame, than probably that so signifies that they will obviously lie about something of real importance, for those that construct little lies, are invariably those that tell rather large lies, as well.
In point of fact, in virtually anything involving deception, such as stealing or cheating, whether large or small, it does not really matter, that person should be seen as a thief or as a cheat, no matter the size of the action, or excuses so made. For, the line drawn in the sand is absolutely distinct, and that line stipulates that on this side, for instance, there will be no lies, and the other side, there is. So that, there is, never, some sort of neutral territory between the two, thereby considered to be neither lying nor truth telling, but something in-between. That is to say, there aren't any small liars, just as there aren't any small thieves, and there aren't any small cheats for each is cut out of the very same cloth. The bottom line is that you are either one or the other, for a house divided will not stand.