If you've decided withholding certain details is for the best, then that's your choice. What I'm trying to understand is why you believe saying you worry about his safety isn't enough to deter him from putting himself in dangerous situations. It sounds like you're concerned you'll wind up in an awkward position if he starts prying for reasons, and that may be true, but is the core reason -- namely, that you don't want to lose him -- not sufficient enough for both of you?