Existential therapy does emphasize personal choice and will, but it does not necessarily contradict two-person psychology. Instead, it provides a different perspective on the importance of the interpersonal context in shaping individual experience and behavior.
Existential therapy focuses on the individual's subjective experience of their own existence, including their experience of meaning, purpose, and freedom. It emphasizes the individual's responsibility and choice in shaping their own life and creating their own meaning. However, existential therapy also recognizes the importance of the interpersonal context in shaping individual experience, and the impact of the individual's social and cultural context on their experience of freedom and choice.
In this sense, existential therapy can be seen as complementary to two-person psychology, rather than contradictory. While it emphasizes the importance of the individual's subjective experience and personal agency, it also recognizes the importance of the interpersonal context in shaping that experience.
Moreover, some existential therapists incorporate a relational approach into their work, recognizing the importance of the therapeutic relationship as a co-created and mutually influential space. This relational approach can be seen as consistent with the broader trend towards a more relational and contextual understanding of psychological development, and a move towards two-person psychology.