BUT here we go,
do not approach delicately, or atleast do not take alot of time to say it.
be honest cover nothing up (for most its easier to justt spit the truth out).
Just explain logically that you still help your friends out by playing wingman for them, you never take any of the girls with you or do anything with them that could be construed as cheating.
Your frame of mind should be that you're not doing anything wrong and that she should not be bothered by it. pull her into your frame
Cheers n good luck,
Smile