According to Adah, marriage is not a bed of roses but a funnel of thorns, fire, and hot nails. Why does she say that?

Adah does not marry for love; she marries to pursue her dreams. She has wanted to go to the United Kindgom since she was eight years old, and she stops at nothing to pursue that goal. Still, even though marriage is the only way she knows to achieve this goal, it also has many challenges of its own.
Even after she finally makes it to London, she finds herself caring for a man who is lazy, violent, and works very hard to crush her dreams. Still, she knows that she must remain married to him despite these difficulties, because the realities of being a Nigerian single mother living in London would be even worse. To Adah, marriage is a "funnel of thorns, fire, and hot nails" both because of its horrors and also because of the ways that she finds it utterly unavoidable.