What and how a parent plans to do towards financing his or her child's higher education is among those many things that should be discussed before marrying anyone who has a child.
The Federal financial aid system in the States is predicated on the principle that primarily responsibility for funding a dependent student's education ( dependent is defined by the government as being under the age of 24, being unmarried, not a veteran or ward of the state, and not having a dependent of your own for whom you provide a documentable 50% or more of your dependents support) is the primary obligation of the student's parents.
The government is totally indifferent to the parents willingness to assist in this process and parents cannot be legally compelled to assist. However, the parents' income determines whether the student qualifies for grants/gift aid and the amount of type of loans for which the student will qualify.
Students who have parents with high incomes and an unwillingness to assist them are at a decided disadvantage. It is not uncommon to see parents who desperately want their children to have access to opportunities that they themselves did not have be willing to go into considerable debt to try and provide these opportunities to their children. Some parents take a you are an adult approach and distance themselves from the process. Sadly, for aid eligibility purposes, the Federal government does not view a student as an adult at age 18 or upon graduation from high school.
The decisions made are often tied to the parents' hopes, dreams, and aspirations for their children. Those who want more for their tend to find ways to do more even if it means putting themselves in debt.