That's not quite right. Trauma bonding is where an individual or individuals in a relationship create a inner sense of turmoil within someone that creates a kind of "if your saying Im Bad then I need to fix it for you". It's based on a punishment/reward type dynamic where someone will go back to something that isn't good for them. It can be and is usually initiated by someone but it can happen spontaneously as well. The difference between an equally dysfunctional relationship and an abusive one. If an abuser realises that that mode of manipulation can be used to obtain a greater sense of control and dependency then they will.
I wasn't at all saying it's anything to do with her choices at all. That timeframe leaves me in no doubt that he was the initiator in that dynamic. She probably didn't know him very well at any point and it takes time to realise what he is about and leave. The extended time in inflicted turmoil is what makes that person react the way she did with being very upset. Without the stress she probably would have just cut ties but I can almost guarantee he has put allot of effort into making her think she is doing something wrong when she isn't. Going from high stress to low stress can in itself be a traumatic experience that leads to depression and anxiety.
"Trauma bonds are based on terror, dominance, and unpredictability. As the trauma bond between an abuser and a victim strengthens, it can lead to cyclical patterns of conflicting emotions. Frequently, victims in trauma bonds do not have agency, autonomy, or an individual sense of self. Their self-image is an internalization of the abuser's
conceptualization of them.
[7]"
en.m.wikipedia.org