Yes you can, I've seen enough people do it.
Including my brother whos been seeing a girl for **11** years, hes cycled, he ran tiny shit like superdrol, hes done EVERYTHING, and she doesn't know a single fvkn thing. All she sees is him eating and going to the gym, so what else is she to assume.
A LOT of guys CAN hide this from their spouse, hes been hiding it for their entire time together and they get alone great. Your girl might be freaking out, but thats your problem bro, you gotta pull on the leash when they start getting out of control. Thats how you build a "successful" relationship, NOT by telling the truth. Gzzz