Just because you're talking to a guy doesn't mean that you can't flirt with others. "Talking" isn't any kind of binding relationship and neither is dating. When and if you actually commit to each other as boyfriend and girlfriend then things would be different. I don't see anything wrong at all till there is some kind of commitment.
Relationships: If a guy says that he would like to think you are "talking" and it is the step before dating does that mean that you are exclusive and it'd be wrong to flirt with other people?
I've been married for 26 years, I will be flirting until my dying day. I'm married not dead.
There is no commitment there. I hope you're talking to lots of people ... And doing a little flirting as well ;)
No ... Because it means NOTHING other than you are friends.
Even dating is not supposed to be exclusive. You need to date lots of people, to determine the type of person you want to marry. If you limit yourself to dating 1 person at a time, it will take longer to compare people and decide on that special person.
That view of the situation would have girls sitting around waiting for a commitment until they are in menopause.