Most of the times, things that happen in a couple have to do with the two parties dynamic. So, it’s up to a point normal that we can also contribute and worsen things bc of our own issues.
I’m sure most of people, say things in the heat of the moment that then, they regret.
Of course, it’s a boundary that never had to be crossed but that’s why taking responsibility and learning do exist.

Found that video about leaving a person with bpd. I don’t see the bpd person as a responsible perse. I think it depends on how her/his disorder let her/him to work on the struggles and being more functional.
So, yes, the video is about leaving someone with bpd but for me it can be spread to any person you can have a toxic relationship with.

YouTube