Welcome Camamo,
I suspect my boyfriend has BPD. We have been together 4 years, mid 30s and live together. We only ever fall out when he chooses! He creates situations so he can get angry with me, i have pointed this out to him and he agrees. Also he tends to do it at the start of his week long breaks from work, so every 3 months or so.
it is good that you have build already some awareness and can see that there is a situational driver for him feeling overwhelmed - yeah, taking a break can be overwhelming after all it is a big change and takes away all the helpful (although resented) external structure. Building better communication skills (see LESSONS) will help you taking a few edges off these mill-stones but in the end he will have to find a way to cope better.
The current situation is he is giving me silent treatment, for the last week, and he has been off work until today. He decided I lied to him about about buying something (a packet of cigarettes) and withdrew from me completely. He got drunk and became really hostile, pinning me down and hurting me, then told me he couldn't bear to be in the same room as me and I had annoyed him for too long. Since then I have been sleeping in the spare room, and he spent his days in a separate room with the door shut, so really we have been avoiding each other.
I'm not sure where to go from here? Should I approach him or wait for him to talk to me?
Apart from his moods he is generally loving, kind and generous but has tremendous self esteem issues and has had therapy for work related anxiety.
We often make matters worse by becoming too reactive on the pwBPD. Try to do your own thing for the time being and start learning validation related communication skills. There is no simple sentence you could say that works. But there are a lot of simple sentences that can help a little to calm things down - which exactly depends very much on the moment and situation and the validation workshops will help you building up the skill to do that.

,
a0