You are basically really bad if someone with a great lance couches you in a head on charge and you can't stop him with a long spear.
Your options are:
Get a pike (it actually costs less).
or
Time your attack better.
The long spear has a length of 245 and you can thrust with it, you can only couch with the great lance. But you can't defeat anybody if you don't thrust at the right time.