hi.if your friend has been diagnosed with schizophrenia
it itself is a very typical psychiatric disorder.it has been classified into different subtypes depending upon the symptoms and the signs of the patient.
a psychiatric evaluation is what is required and that will give the type of schizophrenia and once you know the type, prognosis of the disorder can me made out and so the response to the treatment.
there are drugs which treat this disorder and such people may live a normal life but have to continue with the treatment without fail or interruption.
regular psychiatric follow up is what is required.
and yes schizophrenics can marry provided one is completely aware and willing to accept this treatable disorder.
hope i have helped you.