Polypersona

Polypersona is the phenomenon where people change their personalities in relation to the person they are talking with.
It can be experienced online more often than in person.

Polypersona ≠ mood/behaviour.
For example you being kind to your crush and rude to your teacher is not polypersona.

Jack is "Mary", a female who is seeking a relationship when talking to Jose. But he turns back to Jack when he meets his friend, Matthew. Therefore, Jack suffers from Polypersona.