Most Helpful Guy
What is okay? - texting, talking, hanging out, but to an extent. If they talk more than you and him talk, there's a problem. There are many things out there where you can draw the line, but it's really something you'll have to experience to know.
What isn't okay? wrestling, spending the night, flirting excessively, kissing on the cheek, etc
Most Helpful Girl
I'd say it goes into the territory of cheating if he touches them, or talks to them about personal things instead of you