Dont need a lot of detail....honesty is the best policy. If you dont trust the BF enough to tell, then you have only two choices....drop him or drop zoo. Are you active, or do you just watch? If this is a voyeur kink for you...just drop it. If he doesnt stick, you can pick it up again. If youre truly an active beasty or Zoo.... chances are he'll go if he finds out....spend some time reading here. You and that sit are not unique.