When It's Not a Lie But An Omission

Have you ever asked someone a question and they paused before answering? This should be evidence that the next words you hear may not be completely truthful.  Most of us want to believe what we hear, even if we know it's a lie, but recently when I pressed the point the response I got was "I didn't lie, I told you what you wanted to hear."  Or how about when you are talking with someone and they ask "do you want the truth"?  Are you kidding me no lie to me is what I usually respond.  So when is a lie an omission?  Do we really rather hear "what we want to hear? or do we really want an omission?  I met a young woman who claimed that she NEVER lies I asked how is that possible, because if she had the secret I wanted to hear it, after several minutes she acquiesced that there are times when she "bends the truth" in order to not offend someone.  So is it really possible to go through life and NOT lie even a little bit?  Many times I have been listening to someone explain a situation and I immediately can tell that they will either be the hero or the victim at the end of the story, I think that is our nature.  If people told us stories and didn't embellish we would quickly lose interest so we pepper our stories with OMG statements or can you believe it statements because who really wants to hear the ""truth."  Lying has always been a part of our make up since the beginning, Satan told Eve if you eat the fruit you will have untold knowledge but he omitted, however if you do you will be committing sin, because God told Adam NOT to eat from the tree of knowledge. Which leaves me asking when is it a lie or when is it an omission?