My mum used to do this. Well, I'm sure she still does, but I've been blissfully NC with her for 6 years.
I did find out from a cousin that she'd never told anyone in the family that we're NC. Rather than just not mention me at all, or say "Well we've fallen out, I'd rather not talk about it" she simply started... making stuff up. So now the whole family think I've been doing god knows what with god knows who for god knows what reason. No idea what but all will certainly have been calculated to make me look like a clueless, pitiable helpless child and her as some kind of guardian angel/martyr. Which is laughably far from the truth.
When I was younger she simply told me over and over that things I remembered were not true. "What an imagination you have!" was her favourite phrase. It is absolutely insidious and a horrible, unforgiveable thing to do to anyone, let alone a child. Let alone a child who is crying for help because they are being abused... and to then be told "You have never been abused, gosh you are so strange and funny!"
It nearly destroyed my mental health. I constantly questioned all of my memories, about the most trivial things. She and my dad were so adamant that he had not abused me. Surely I must have been crazy and living in a delusional world? And wasn't I irredeemably wicked to make up such terrible lies about my own father?
It's only been in my 40s that I've been able to see her narrative-twisting as the harmful, brain-melting abuse that it is. In many ways its been more harmful than the actual abuse (serious sexual assaults on a daily basis for years) because at least with direct abuse you can say "This happened, the abuser is an evil bastard, it's now over."
But how can you heal from something you're told didn't happen?
I've recognised in myself a tendency to do the same, that's the most frustrating thing. Not that I tell anyone that XYZ happened or did not happen - but a tendency to paint myself as a helpless victim of circumstance rather than as the product of my own choices and work.
For me, giving myself permission to make the wrong choices sometimes, and to retrospectively forgive myself for them, has been the key to letting go of this behaviour. Because for me, that's the key - I didn't want to accept that I was a human being and capable of making bad decisions. I needed to believe that I had no choice in (for example) leaving school, not going to uni, taking that job, leaving that job, shacking up with that man, leaving that man, marrying another man, leaving that one... etc etc. If I believed I had no agency, then I didn't have to take responsibility for myself, or learn from my mistakes. I was keeping myself in a permanent victim/child state.
Now (with a lot of therapy!) I've been able to let do of those damaging narratives and remind myself that the reality is: I'm a fallible human being just like anyone else, and at times I've made bad choices. Once I recognise that, I can then commit to learn from those choices and not make them again. If I keep saying "But I HAD to!" then I'm free to keep repeating the same mistakes over and over.
OP It might be worth persevering with your fella, if you believe that at heart he is a good person who loves you. You did mention that he's "pretty selfish" which doesn't bode well. But I do believe that people can change - if they WANT to. Change is hard work.