How can this be regarded as adultery if you dont see them, talk about haram things or are tempted to meet them and do haram?
Answer:
If there is no need to talk to the opposite gender who are non-Mahrams (not prohibited in marriage), then that is a sin.
Shari?ah strongly advocates separation and segregation of sexes. The evils of intermingling of sexes and free communication between them are well known. In brief, it is death to a pure and clean heart and mind. It is death to spirituality.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai