Doubts tonight. Was it me?

I did not know exN's last girlfriend. They dated for 10 years, and broke up but remain on very good terms. I know of two girls that he cheated on her with (he only kissed both of them, but who knows if there was more cheating that I did not know about). She got married maybe 6 months after she split from exN. He talks so highly of her. How could she not have the same experience as me? How was there no horrible discard? How was there not a massive smear campaign launched against her? He dated briefly for 6 mos before we got together, and he talks such shit about that girl (and sickeningly enough, now I'm pretty convinced I was the OW to her but had no idea :( ).

I obviously can't judge his long relationship and if it was healthy or not since I know no details. He was 18-28 while they were together, so maybe his disorder is getting worse the older he gets (34 now). Or maybe he isn't a narcissist and this was all me being a horrible person to date.