Hi Magokoro and welcome.
It's difficult to get into arguments with a partner whom we have loved over several years. It makes it more difficult when there is BPD involved. You're not alone here--you'll find people with similar situations to yours.
When a person is going through a lot of stress, that agitation can often show up in unexpected way or over nothing obvious. It's more confusing when things seem to be going well are met with distance. I realise that can feel like a rollercoaster. Adding to the issues are when blame for many inexplicable things get heaped onto the partner--as you're feeling. Sometimes when people have nowhere to run, they may start to blame people close to them for things where responsibilities aren't clear. This can show up more in relationships with a pwBPD partner.
I do appreciate that all of this is very confusing for you because of the mix of opposites with a lot of the things he's expressing and with those things you're experiencing. It gets even harder when we've relied on this person to recover from something very difficult for us.
I encourage you to visit the Acknowledgement step here:
https://bpdfamily.com/detaching/01.htmPlease do share how this develops for you. You can find support here.