Marriage plays an important role in the book.
Mariam's father could not marry Mariam's mother, despite the fact that polygamy is acceptable in Islam. It's pretty obvious from the book that Jalil (Mariam's father) was embarassed by the fact that Mariam's mother was a servant and the daughter of "a lowly stone carver." As a prosperous and respected member of the community, he could not have accepted Mariam and her mother into his family without extreme loss of face.
Jalil did support his daughter and her mother, and visited Mariam weekly. In that aspect, he accepted responsibility for his actions. However, he could not publicly accept or acknowledge his daughter.
Jalil's response to Mariam publicly forcing her way into his home was to marry her off to a prosperous business contact. Marriage is honorable and expected in Islam. While the timing of Mariam's marriage was rushed (no doubt sped on its way by Jalil's three wives who were probably writhing in embarassement from Mariam's presence in their home), Jalil was trying to give Mariam a safe and comfortable home, after the death of Mariam's mother.
Mariam was unspeakably angry by his actions.
In Mariam's shoes, would you have been angry?
In Jalil's shoes, what would you have done?