Who is Herbie from The Contract with God Trilogy: Life on Dropsie Avenue and what is their importance?

Herbie is a medical student and intern. He travels to upstate New York for the summer, where he works as a musician. Herbie is described as a kind, friendly man, who wears glasses. When he meets Goldie, she initially snubs him because she is looking for a rich man. Yet, after she is raped, Herbie comes to her rescue, and the two end up marrying.