Therapist: The ability to trust other people is essential to happiness, for without trust there can be no meaningful emotional connection to another human being, and without meaningful emotional connections to others we feel isolated.
Evidence
Without trust there can be no EC → T meaningful emotional connection to another human being.
Without meaningful emotional ~FI → EC connections to others we feel isolated.
Conclusion
The ability to trust other people H → T is essential to happiness.
Evaluate
The argument assumes that H → ~FI happiness requires that one not feel isolated.