What colours would go best with this wallpaper?

That's a gorgeous wall paper! I'm not sure if your planning on painting the walls, the same color or differents colors, but if it's the same, most deffinetly the same pink in the wallpaper (make sure it's not to dark or light...it won't look good with the wallpaper)! If you want it different I would say pink and either lime green or a grey. That is your own opinion. I think a light green would look really good though, and my room is a super light green, and it works really well on the walls, though not many people seem to think of painting there walls that color. Good luck with your room, and hope it turns out well!