The U.S. Constitution plays a role in family law. What is one right the U.S. Constitution gives?

Liz and Darius have been dating for six months, since Liz separated from her husband Doug. When her divorce becomes final, she and Darius plan to get married. There is a clause in a draft of their divorce decree that discontinues Liz's alimony payments when she remarries. This restriction is an example of:

Naomi and Rob have been a couple for five years. They have not married because Rob is receiving spousal support from his ex-wife that would terminate upon his remarriage. He needs that money because he is the custodial parent of an 11-year-old son. If Naomi and Rob get married and challenge the provision, the court will strike it from the divorce decree.

Randy is a 40-year-old virgin. He has spent his entire adult life caring for his invalid parents. His mother died two years ago and his father recently died. Although he was sad to lose his parents, Randy felt he could finally make a life for himself and perhaps get married and have children. At the reading of the will, he discovered that his father's will stated he would forfeit his inheritance (valued at $2 million) if he married. If Randy contests this clause, how will the court rule?

Agnes recently joined a dating service because she was recently divorced and lonely. She thought that the initiation fee of $1,000 and monthly dues of $50 were a little high; however, since the group emphasized marriage she signed the contract anyway. She neglected to read the fine print that stated each time a member marries an additional payment of $2,000 is payable. Since it was in writing this provision is enforceable.