It happens. Wood gets dry, old, cracked, and cannot support itself or the artwork in it. What is especially upsetting is when they commit suicide and take the big leap off the wall to their demise.
Sometimes the leap is an unsuccesful attempt and just the corners separate and can be repaired, repinned and glued. Ahhhh, you are relieved. But lots of times, the antique frames found at the rummage sale, in the attic, or the old frames that have been hanging for years may not be in the best shape to be revived.
It is hard to hear this news from your framer, but take heart. The art is what is important, and reviving it with a new frame may be just what the "doctor" ordered, and give you a whole new look to enjoy.