Hmm, so she can see through that textured glass? You could do a roller shade. We just had Hunter Douglas come out to do some windows, and that's what they recommended for a window in our bathroom. However, the metal parts of the shade are not guaranteed to never rust, so you could have to replace it down the road. A top down/bottom up would be good too since you could have it open only at the top and allow light while having privacy. I ended up doing a nice tension rod with a custom curtain that hangs inside the window frame. You could do the same but hang it like a cafe curtain.

I would go to a big box store and get a roll of the textured window film and go over it. I bet a second layer would give you more privacy without blocking much more light.

I bet your neighbor can see shapes only at night, and nothing detailed. Small comfort...

There are lots of different levels of privacy on window films and I'm sure you can find a good one.

Or commission a big version of your stained glass. :)

Whatever you get, take turns with your partner peeking in from the outside at night.

Tou also can use a more opaque film on only the lower part of the window, if no one can see over the top. Or plantation shutters on just the lower part.

In addition to window cover inside look for appropriate landscape feature outside window.

You need to get a more opaque window film. Look for the websites that sell window film and you will see a lot more options than the ones you find at HD/Lowes.

I had this situation at my last house.

I bought TWO shower curtains - one for regular shower curtain use, and I cut the other one down to hang over the window. The rod was mounted several inches above and several inches wider than the window so there was enough coverage.

There are varying opacity levels available with films and different patterns, textures, etc. With your current window, all anyone can see is movement. Detail cannot be made out through that type of glass/film. The ability to see movement is affected by the lighting in the room and your distance from the glass.

If you don't want anyone to know you are in the shower, you will need a heavier cover to block more light at night.

i would prefer a clear window ..so i could see when there is anyone outside…..adding a curtain or shade that offers privacy when needed….until such time as the proper kind of window can be installed there

What if you consider the problem can be solved by doing something on the exterior? No image of the outside of bathroom or what you would have to do so inquiring neighbor can't see in, just an idea. You get natural light and neighbor gets, well, nothing.

Home Depot

I bought a one inch white nylon or poly (?) blind from Home Depot, cut to fit, can be louvered up or down with wand, or rolled up, or whatever for the amount of light you want; down and closed while showering, total privacy, water does not harm it at all. I like having the light come through when I want it. Inexpensive! I can slip it out of the brackets now and then to clean it a bit, then back in it goes.

Translucent film and also translucent glass is not enough, you can see shapes and colorations right through it esp. if anyone is close to the window, and esp. at night. Just blurs it, not good at all. Need another layer.