We are ALL warned!!
Galatians 6:1
“Brothers, if someone is caught in a sin, you who are spiritual should restore him gently. But watch yourself, or you also may be tempted.”
(I get ‘tempted’ all the time!)
The “temptation” is that of sin. The original point I made was that particular behavior was not a sin because I get my definition of sin from violating a commandment which does not include fornication, only adultery.