When taking pictures of couples I easily get stuck after three or four poses. What helps me is a little sketchbook I always cary in my camera bag with illustrations of poses. Why illustrations and not photos? That's a good question. When I look at a photo, I'm usually drawn into taking exactly the same picture and frame it the same way. On the other hand, with illustrations, I tend to be more open. I always try to shoot different pictures, from details to wide shots in order to get everything out of one pose.
I hope this helps you on your next shoot. Let me know.