I was in a relationship with a pathological liar. I think I've mentioned here somewhere that pathological lying isn't considered a disorder in itself, but is something that seems to be a consequence of some other mental disorder.
The person I'm thinking about, my GF and her lies, seemed to be initially at a low level, inconsequential perhaps. But slowly, over time, became more significant, more complex and interwoven with other lies. I was told at the time by my GF that she was being assaulted by her ex as she walked home through a park after taking her daughter to school. That alleged assault took place where there was no witnesses. She did go to the police. She informed me that the police told her that her ex was being investigated for drug dealing and that the ex was paying people to spy on and to follow me. How do I know she did genuinely go to the police? Well, that's another story for another time.
Anyway, eventually I saw her ex driving in his car. I chased him down and confronted him, only to be told by him that my GF had been telling him that
I was being investigated by the police and that
I had been assaulting my GF in the park. It became apparent that we were both being told the same lies of each other by my then GF.
At the time, my GF had cancer, 'allegedly'. It was really challenging for us to both see her doctor or hospital specialist together. Her appointments would change at pretty much the last minute, and be brought forward, 'allegedly', at a point when I was at work. We did eventually go to the hospital together, to see a specialist for a non-cancer related issue. The specialist had my GF's medical records on her desk as we went in. It was the biggest medical folder I'd ever seen, but even the specialist admitted that there wasn't a lot of any great significance in it. Can you see where this is going?
On another occasion I was unable to go to a hospital appointment with her because it was canceled -- it was deemed unnecessary due to an 'event' 24 hours earlier. She called me at work to say she had been rushed into hospital by ambulance, and therefore the following day's hospital appointment was canceled. She came out of the hospital the same day before I got home from work.

It was a kind of, "
Yeah, right?" moment.
Later after the relationship ended, and when talking with others, I 'discovered that my GF had had small colon cancer; large colon cancer; ovarian cancer; cervical cancer; stomach cancer; leukemia; and at some point, a brain tumor. It seems that some people felt sorry for me being in that relationship, but at the time didn't want to get involved by telling me of her history. I suppose that is where part of the problem lies when being drawn in by a Pathological Liar, most people who already know the liar don't want to talk about it thought fear of being involved.
Previously, in a letter she wrote to me, she told me of a particular cancer she has, and that she only has one year left to live, two at the most unless a miracle happens. I don't believe in miracles, just in case you were wondering. 25 years later, she is still alive.
If you are interested in how that relationship ended, you can read it in this SF thread here. Prepare yourself:
Ever had to extricate yourself from a difficult situation or relationship?