Wife, yes. If you have to hide something from your wife, you might want to reevaluate your priorities. My wife is fine with me having gear in the house, and she'll pin me if I ask. We've already spoken about it, and she didn't bat an eye at me wanting to use AAS.
Girlfriend? Define girlfriend. In my single days, I went though lots of "girlfriends", but most of them I wouldn't trust with anything other than my phone number. I suppose if I was with a girl that I was planning on asking to marry me, I'd trust her enough to tell her, that goes back to my first statement. The chick that you're banging for a few months? Probably not