Non BPD haver looking for advice and perspective: The gist is that I'm not sure how (or whether) to hold my partner accountable for actions of theirs that harmed me, but that are a likely symptom of BPD. My thinking is that a) I don't want to enable them, but also b) I have difficulty blaming them for something that quite literally is a mental disorder.

A summary of the specifics, trying to keep it as brief as possible: Both me and my partner live in the UK. I had to travel the U.S. for a major surgery last month. The surgery itself is very intense, but as a compounding factor I have PTSD from medical discrimination, so I knew this would be a difficult time for me. My partner kindly offered to travel with me to take care of me. I was worried that international travel would be too stressful for them, but they insisted they'd be just fine, and eventually I agreed. They put their live on pause to travel with me on short notice, I paid all their trip expenses.

Unfortunately it turned out that the trip was indeed too stressful for them, leading them to exhibit coping mechanisms I hadn't seen before, and that I felt were really selfish. This included getting really high on weed at a time when we I had discussed I needed their support, and hence not being there for me when I received some very bad news. Being very mentally absent, asking me if they could date other people on the trip (a week post-op!)), coming to me to vent about their life's problems and wanting to quit college while I was recovering, coming to me to vent about being sad that they couldn't explore the city because I was staying home recovering. A lot of small interactions too numerous to recount individually, but that in their totality accounted to them being very self centered during the trip. This was really hurtful to me, because they had promised to take care of me. And instead it turned into them constantly relying on me with support for their emotions related to regular life problems, as I was literally recovering from surgery. To me they acted really selfishly, which surprised me as I never saw them like that before.

In hindsight I think I can understand that International travel was very stressful to them due to their low distress tolerance. This leading them to act selfishly as an impulsive coping mechanism, and thereby unwittingly betraying the fact that they do care about me, and that they promised to take care of me. I do think they care on some level (they put their life on hold after all to travel with me) but in practice they did not show this at all.

It's still extremely hurtful though. Like in totality I feel as if perhaps it would've been easier to travel alone. This is given how much energy I ended up expending on caring for their needs (while I was in a worse situation) and given the pain of being abandoned when I relied on them most. There's also the almost $3k dollars I paid so they could travel with me.

How do I move on from this? I understand what made them act the way the did and that it seems like part of BPD and hence perhaps not their fault. However I also do not deserve to be treated like this.