Is it disrespectful to flirt with someone else in front of your friend with benefits?

Even though you are friends with benefits and not committed do you think it is rude or disrespectful to flirt with someone else in front of the person who is your friend with benefits? Guys, if your fwb flirted with a guy while you were hanging out would that be uncool? Ladies, if your buddy flirted with another girl in front of you would that be a slap in the face? Should flirting and trying to hook up with others only happen when they are not around?