No, these birds are too different in size to put in the same cage. Your lovebird that you are calling Dutch face is actually called a Dutch Blue Peachfaced lovebird – this is a mutation of the normal Peachfaced lovebird. So the only suitable mate would be a peachfaced lovebird – either a normal or a mutation. You need to be sure it is a peachfaced lovebird mutation as other species of lovebirds will not get along with the peachfaced. If the birds were bonded, you might try putting the bird outside in a secure cage, with an open cage next to it and see if it will call and attract the other bird to return.
Thank you for asking Lafeber,