Most Helpful Guy
Just bring up your boyfriend in general convo and be sure to mention just how awesome he is at being your boyfriend. If that doesn't work, suggest hooking him up with a friend of yours. Another option would be to take your boyfriend to get coffee with said 'flirter'. If he doesn't get the point after you've employed all of these tactics, tell him you have an STD OR, as a last resort, have your boyfriend stomp a mud hole in him then kick it dry?