Firesprite-
Though they were two different people in my life, as I was coming to understand that my ex was struggling with drinking my best friend in town was struggling with bipolar disorder (undiagnosed). You can imagine the mess that I was as a result (I am much better now).
She is excellent about taking meds etc but it did take awhile for her bipolar to come under control because there are different types of the disease. She has a type that is called rapid cycling and she can have mood changes up to 15 times a day. This is not typical for bipolar but it is part of some people's disease.
It was really helpful for me to understand that about her disease. It allowed me to be healthy toward myself if there were changes in her demeanor that I was not anticipating in quick succession (that is all about me and my recovery, not hers).
She had previously struggled with other addictions in her life, but not alcohol so I don't know how they overlap.
Similar to loving a person that struggles with alcohol learning to handle myself in the midst of a loved one's disease was complex and came slowly for me. I am interested to see what others post so I can continue to learn.