How is it possible to marry someone with a mental disorder?

My mother is doing well on her medications. During my HS years, my mother suddenly started hearing voices and seeing things only she could see. She got diagnosed with Schizophrenia and has been under medications since.

Supposedly my father met her as a beautiful and healthy 19 year-old at the time. I would like to think there must have been some red flags. How did it go undetected to the point he married her? My parents are still together.

How is it possible to marry someone with a mental disorder?

How is it possible to marry someone with a mental disorder?
Post Opinion