We hear a lot about toxic masculinity, not so much about toxic femininity, yet both are equally destructive for relationships. So, the question is what makes these toxic? In a broad sense, pathology has two characteristics: first, it doesn't learn from its mistakes; second, it doesn't tell itself no. As a result, pathology or toxicity is unregulated; in other words, pathology does not self-regulate.
In relationship terms, when a man and woman meet, they often place their lives in each other's hands and take on the responsibility of making the other person happy. The problem with this approach is that it sets both people up for a lack of self-regulation and creates expectations that the other person should meet their wants and needs based on their actions. This initial act is often completely unconscious yet thoroughly toxic.
This results in a zero game mentality where one person's advantage equals another person's disadvantage. It also establishes a relationship based on fairness, reciprocity, and mutual deserving, setting both people up to measure their actions based on their partner's behavior. This results in a centripetal or moving downward spiral where the relationship ends based on both people getting the short end of the stick every time.
If this process doesn't work in relationships. What process does work?