Very weird. No signs of worms or anything? You might ask over in the rose forum. I have several roses in my yard and I've never seen anything like that.

If you're going to snip back - go to a leaf node where the leaf has five leaflets.

Might help if you stiffen the stems with a dose of tomato food - for the potash.

Look for disturbed dirt within a yard of your plant. Pocket gophers are very active this time of year and prey on blooming flowers in my garden. Let me know if you see any holes or piles of dirt and Ill give you the long list of what hasnt worked for me and the short list of what has worked. Good luck! Theyve been eating every blossom they can find in my beds.

i also have been beheaded, roses but seedlings. I though it was cut worm but they usually chop from the bottom near soil level. Ive also noted pieces of iris flower petals all the way across my gardent, very strange. May be birds.

Gloria in Westminster