Is a diagnosable mental illness a red flag for you?
To answer my own question:
A the person afflicted has not sought any treatment or kept up with treatment in the last year
B us being together and/or being poly has for the last two years objectively made them worse
C if their condition is very similar to mine, involves a lot of mood swings and shifts in identity
D they are using drugs and alcohol to self-medicate
Me: bi female in my twenties