I just was surprised to read about how many times she was married; she leaves Liz Taylor's marriage record in the dust.

when she was nine-years-old in 1957, schoolmates humiliated her over a pair of pink suede shoes.
Yes, she overcame a lot!
On a more serious note, while one could easily dismiss O'Neill's misadventures as "white girl problems," I think people also don't always grasp that being a phenomenally beautiful woman (with just an average intellect) can come with its own insecurities.
If you are in an industry that praises you only for how you look (Ms. O'Neill has no acting talent to speak of) and men are constantly declaring their love for you based upon those looks, surely you'd have to start wondering if you had any internal worth. One car crash with some glass to the face could essentially wipe you out!
So in that sense, I can see how she could easily have had some emotional issues to deal with.
.

At least she's better off now. And hey, we'll always have Scanners.