The issue is that his income means that your income isn’t solely paying the household bills…
Single mom earning 80k per year has a lot less to contribute to college costs because she pays all household bills.
Remarried Mom earning 80k per year with Hubby earning 80k per year is splitting household bills and therefore should have more disposable income to put towards college.
Then they would have multiple children in college at the same time and EFC adjusts for that. That said, many delay remarriage so that new spouse income won’t count.