If someone with BPD is willing to work at improving their condition, things should get better.

Wanting to stay in bed all day, after 8 months on a medication regiment, doesn't sound like the meds are helping. Naturally, meds alone won't help, how long has she been in therapy? Is one of the sessions DBT-based?

Being involved for 8 years, is a long time. Are you, also working with a therapist, to help you learn how to communicate with your BDP fiancée?