Abusive relationships are fairly simple. They are driven by insecurity, fear that feeds that insecurity and an expectation of inconsistency, both real and perceived.
An abuser is morbidly insecure. S/he (yes, potentially, she) has little sense of his/her own social value and makes an effort to gain or re-gain some semblance of that value through domination and control. The fear that feeds that insecurity has two fronts: fear of not being lovable, and fear of appearing weak. The paradox here is that the abuser is, in fact, weak, which is why s/he abuses — to maintain a sense of control — in the first place. The perceived inconsistency on the part of the abuser by the victim is that the victim is not submitting to the abuser’s domination.
The victim is also morbidly insecure and for surprisingly similar reasons. S/he also has little sense of his/her own social value, but makes an effort to establish that value by losing him/herself to the demand for submission. The fear that feeds this insecurity is also about not being lovable or loved, and there is a willingness to accept the inconsistency of the abuser’s attention for the sake of being loved.
The pathological need to control on the part of the abuser and the pathological need for attention on the part of the victim is a match made in heaven. We are all just a bunch of neurotic habits that tend to find a fit with our opposite to create a psychosocial balance. Abusive relationships are one of the most extreme cases of this dynamic.