Is Flirting On The Internet, Considered Cheating?

The question was posed to us if flirting on the internet, by someone who is married, considered cheating.

If someone is married, why would they think it’s permissible to flirt with anyone other than with their spouse? What about Internet flirting? Aren’t they putting themselves into a situation where they can fall into temptation? They’re playing with the emotions of someone else who shouldn’t be flirting with someone who is married. Isn’t this called being a “stumbling block” in tempting them to sin?