It's not just men that lie, but that is neither here nor there. I think some people lie to make them selves feel much better about a situation, making someone else take the blame for something they can't face them selves.

Case in point, my ex-wife lied saying I was sleeping around on her and that the whole thing was my fault (so I know where your coming from.) When in truth she , my ex, could not handle the situation at home. Grass is always greener on the other side sort of thing.

As far as when to call it quits over a lie, I suppose that depends on how important it is to you. You not alone in your situation and questions.