Good observation CastleofGlass
And this is where boundaries really help! Why? Because right now your relationship is enmeshed - there is no clear beginning and end to the ego of the partners. It is not always
instinctively clear who is responsible for what. Emotions swap back and forth in an unhindered fashion. There is little filtering going on. Boundaries change this dynamic in a big way as the lines surrounding the ego of the individual become less blurred. A in some way paradoxic side effect of not being able to dump any toxic thought without feeling she is crossing a threshold will be that she is then forced to look for other outlets or start regulating her own emotions more. With more boundaries and thus stronger egos it becomes harder to deny that an issue is obviously on her side and needs handling by her.