See, you're trying to guess this guy's character from his letter. We have to do that to a certain extent, if we want to understand his situation and try to give advice that is actually good for him, not simply what he wants us to hear. But you're going far. Maybe you're right, and he's a patological liar; but maybe you aren't, and if you aren't, then your whole hypothesis + advice falls apart. It would be better to consider both possibilities, and show how each would influence the advice you'd give.

Let's make it clear: nobody likes patological liars. If I had had a relationship with someone like the liar another commenter her wrote about -- who created a whole life out of his lies on top of lies -- I'd run screaming as if from Count Dracula. Fortunately I never had to do this; I was rather lucky with the people I became interested in. I understand that many people did have to suffer from pathological liars, and I'm sorry for them.

But there's a world of difference -- a complete continuum of variation -- from this patological, pathetic liar and people who told one or two lies to seem more interesting (say, a woman lying about her age?) and then had to keep up for consistency.

By now, there are lots of things the LW's girlfriend show know about the LW's personality and way of being, and above all, she should have some idea of what feelings she has for him. I'm crediting her with intelligence and common sense, enough to be able to see the lie in the perspective of what she knows about him from direct experience, and decide if he's a pathological liar or not. Is that so bad?

So, I'm sorry for all those who had to suffer from a relationship with a pathological liar. But was this the case for every person who aggressively condemned the LW here? Could it be that, in some cases, these people became disappointed with someone who was not a pathological liar, who simply made a mistake, and who got then dismissed as if s/he were a pathological liar? Maybe because American culture is so concerned with it? Frankly, I've never really understood the line 's/he's lied to me about that, what else has s/he lied to me about?' -- doesn't that always depend on the topic? On the amount of lying? On the intention of the lie? And if one has eyes to see, can't one notice in the personality of the person one has been seeing, how s/he deals with others, with everyday problems, etc.?

I still maintain: my wife lied to me about sleeping with someone else (a man I also knew), she did it not only once but several times, and she even made up excuses and alibis. I only found out after I asked her to marry me (she felt then she should be totally honest). I was really angry at first, but I thought about it, I talked to her, I even talked to the man she slept with, and after a week or so I realized this hadn't had any real meaning. So I forgave her completely, married her, and have since then had absolutely no reason to doubt that marrying her was the best decision I've ever made. You see, despite this lie and the cover-up, she was not a pathological liar.