Just use a virtual encrypted drive like
Bestcrypt
No point in explaining why some of your folders have passwords to access them. Unless she knows precisely what to look for she wont even know the drive is there. And if by some miracle she ever found the drive there is no way she could get access to it anyways. This way you can still keep your files organized without having to hide them all over the place or give them inconspicuous names.
I'm lucky I guess, my wife knows what I do so I don't have to worry about hiding porn.