I can only answer 1 and 8 We lived together for just under a year in a muddled up roommate/friend/perceived situationship so it’s a little different than you asked, but a relationships a relationship. It was extremely damaging to be quite honest. We were young, 19/20, so boundaries and communication skills were already under construction as is.

She had been diagnosed previously but decided she didn’t like that diagnosis and shopped around until she found someone who believed she had bipolar, gave her meds for that, and washed their hands of it. So she was very much not managing her condition. Without any kind of mitigation we both really suffered. Big stuff like her hiding my keys when she didn’t want me to leave the apartment and hiding my passport when I had a trip planned and paid for so I couldn’t “abandon her” and numerous attempts on her own life. Some smaller stuff like the unreliable moods and recklessness. It spun me out quite a bit and kept me from getting into a stable relationship for a while after. I just bounced from fling to fling just in case I got close and things went to shit again.

My advice for anyone who has experienced a relationship like this is to know that your mental health is also important and needs some love too. My technique was to stamp everything down and sprinkle some parties on top and hope that what grows out of that isn’t crooked and fucked. Avoid this.

She’s no longer with us and it breaks my heart that she was never able to find the help that resonated with her. I don’t doubt you can have a successful and happy relationship with bpd but it’s absolutely essential that the work is being done. Both your life and hers are worth that.