Dishonesty is to act without honesty. It is used to describe a lack of probity, cheating, lying or being deliberately deceptive.

Cheating refers to an immoral way of achieving a goal. It is generally used for the breaking of rules to gain advantage in a given situation.

Flirting or coquetry is a sexual activity involving verbal or written communication as well as body language by one person to another, suggesting an interest with the other person. The person flirting will send out signals of sexual availability to another, and expects to see the interest returned in order to continue flirting. Flirting can involve non-verbal signs, such as an exchange of glances, hand-touching, hair-touching, or verbal signs, such as chatting up, flattering comments, and exchange of telephone numbers in order to initiate further contact.

there are no grey areas. 

there are no "levels"

cheating. lying. flirting. 

dishonesty.

it's just is.

there's no "harmless" form. 

all you end up is hurting the people who love you.