My pachysandra is quickly disappearing-leaves and flowers in a bed that I have had for thirty years. From thick and lush to only stems and roots. The loss is spreading across the back of the house and now up the side. Does anything eat it? Deer, rabbits, and groundhogs are all possibilities for our neighborhood in Columbia. I have never had any problem with pachysandra except maybe too much! Could the pine tree be the culprit? It is at the corner of the house. I had trouble growing impatiens in that area about three years ago (fungus?) and haven't tried since. My yard is shady with oaks, maple, and beech and the one pine tree. Everything else looks fine.
Howard County Maryland
We've been getting a lot of questions about declining pachysandra. Yes, deer have been known to eat it, though that is not a common problem. You should be able to tell if the tops are snipped off.
Most recent pachysandra decline is related to weather and disease. Two summers ago we had abnormally high levels of rain. This led to a great deal of fungal disease in many old pachysandra beds. It weakened them. Here's what to do about volutella fungus: https://extension.umd.edu/hgic/topics/volutella-dieback-pachysandra-groundcover
Then, last summer, we had an extended drought. Combined with the volutella, it hit many pachysandra beds hard. You mention a pine tree. Usually pine trees have very little growing under them, because their extensive roots out-compete other plants for water. That kills plants under them.
Clean up what is there and follow the advice in the link above. Keep in mind that (Japanese) pachysandra is considered a non-native invasive plant, though it is primarily a problem when it is allowed to move into natural or park areas. There it smothers native plants that wildlife need. If yours has spread too far, now if a great chance to rein it in.