Could it be a motor mount, or something in the gear shift itself.
Why does my car act like it is harder to change gears? on 1996 Chevrolet Lumina
Yes could be a mount causing a bind or linkage probs. Recommend having looked at by a tech before gets to where you cannot shift at all. If is just one motor mount and you let it go can cause the other mounts to stress and go out prematurely.