Nope, blue and green are close on the color wheel so it should be ok, depending on the shade of the blue and the shade of the green.
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I was hoping for something a bit more dramatic, but that is a nice colour too.
Nope... It is her choice. If she is comfortable with it then it is perfect.
Changing her shower curtains from red to blue. I don't know if this was a good choice because her bathroom is green. Will it clash with the rest of the room?