So long story short. My best friend started dating a boy online. After a week of talking he tells her that he has DID (not diagnosed nor went for therapy). So after 3ish months of dating (strictly online he lives in another country) he became close with one of her friends and his alter started dating her too . His stories don’t always line up and i brought this issue up to her. She completely blocked me out of her life and i don’t blame her for that but i do think shes being tricked. And if he’s not faking it . Is it common for a person with DID to have multiple partners ? 
How should i approach her ? Any tips ?