My only concern with the "less is more" solution is that it doesn't prep either party for the potential for a future chance social encounter. By saying instead "there is a remote chance of our civilian lives intersecting" and refusing to say more, she can at least gauge how he might react in that situation and how far she needs to go to avoid it.
Originally Posted by Tim the Enchanter
As odd as it is for me to actually agree with Tim, I have to here. Part of the issue is that even if you break it off, it appears that your social circles will collide someday soon. He needs to be prepared for that so that he can handle it smoothly when it happens.
Eliza, I gather that this guy has some degree of financial success -- and with that has probably come some degree of sense. Yes, guys can go psycho, but if he was that type, he would have shown tendencies along that line for a while (you said I think that you see him at least monthly.) The odds are that he has as much to lose from a crossing of that line as you do. If you approach it like Ansley/Tim suggested, you have the best odds of both getting through that inevitable meet & greet without incident.