Sorry for my delayed response. Then definitely start with encouraging her to see her doctor for a complete physical ... chemical imbalances in the brain are big, big problems. It, alone, can destroy a person's self esteem and confidence. Hopefully its not a bi-polar issue, but depression will ******* a relationship in no time and it won't be her fault. If she's going through menopause, that causes chemical imbalances as well ... you never mentioned your ages.
In the meantime, suggest you not follow through with the "lifestyle" desires, that only complicates the issue.
Very Best Of Luck!