My guess is that this excuse is used by a woman who is into bad boys ... she knows deep inside right from the start who she is dealing with, but she hopes she'll be able to tame this one. When it doesn't work out, she'll trot out that excuse to some poor sap she's willing to settle for and who is naive enough to believe her.
Another way a woman expresses this is with the: 'I was in a toxic relationship' whereby she portrays herself as a victim. In reality, what she's saying if you read between the lines is that she is a toxic person, otherwise it wouldn't have been possible for that relationship to start, let alone continue for however long it did.