I think its hard on carrers when something like PTSD happens after years into the relationship... or at least when it really showes up anyway. Then they have the memories of the person they loved before.. and sometimes I think its hard to almost sort of give up that person as lost.. and then keep on loving this new person. Carers don't stop loving the sufferer but for some the loss of the old person can be to much.
Just a different perspective for you! Hope the hollidays go well for you all!!!