The way I see it is if she has to ask, she's too ignorant(I mean this in the most endearing way) to deserve the truth at this point in your relationship. However I do think it's straight up retarded to be in a LTR with a girl where you need to hide your gear use. I know guys that have their own ritual of how they take injections w/o her seeing, hiding their stash, etc. IMNSHO if you don't trust a girl enough to know she won't freak out and call the cops, your priest, your mom, etc. when she finds your stash, you probably shouldn't be living with/dating her in the 1st place.
Guys go to extreme lengths to keep their supply of ass in check. Personally, I think it's too much work to hide it. I'll just stick with the chicks that are already familiar with the bb lifestyle as opposed to the ones that I've gotta convince what I'm doing isn't as bad as the media says. I've made exceptions in the past for certain girls but it seems like as soon as her friends hear about it I instantly become Chris Benoit ready to rage at any moment. Usually it's just her friend's jealousy masked with genuine concern for her well being. Therefore I'll stick to the ones that already know what's up. Fortunately I live where there's no shortage of figure competitors, gym hos, etc. I might not be so picky if I lived in the cornfields of Nebraska or the dairy farms of Wisconsin though.
Betrayal comes in many forms-a needle in your ass w/o her knowing or her cute co-worker's dick in her ass w/o you knowing. Same Shit. A lot of guys won't like hearing this, but if you don't respect your girl enough to be honest with her, or not lie to her by omission, your relationship is probably a joke. I'll die old and lonely before I end up in a relationship w/o mutual respect, trust, and total honesty. Just my 2 cc's.