Yes. While the basic style is formed in childhood, significant adult relationships or psychotherapy can alter it. There is a concept of "earned secure attachment," where an individual overcomes anxious or avoidant patterns through self-awareness and healing.
It’s a common trap: the anxious partner seeks constant reassurance, which overwhelms the avoidant partner, causing them to withdraw. This withdrawal confirms the anxious partner's fears, leading to more pursuit. This "pursuit-withdrawal" cycle is often mistaken for intense passion.
Yes, it is possible. You might feel secure and calm with friends or colleagues but display intense anxiety or avoidance in romantic relationships, where emotional vulnerability and the significance of the partner are much higher.