It is rare that a Prince marries his BabyMama (which probably is a reflection of society). Usually she fills his nursery and his private quarters until the prince has to make a suitable public marriage. If she is done right by, the BabyMama gets financial support
to maintain herself and children in comfort like Tamara Rotolo and Nicole Coste. (Prince Albert of Monaco refused to marry his 2 BabyMamas but did provide for his children.)
If her luck had run out, the BabyMama might find herself in the situation of Dorothea Jordon. At the split from the Duke of Clarence, he got the sons and she had custody of the daughters with finances as long as she stayed off the stage. Unfortunately a son-in-law got into money troubles, forcing Mrs Jordan back to work. With the deal breached, the duke got the children and withheld the money. Mrs Jordan ended up living near Paris with limited means.
In 2001, Prince Pedro, the only son of Princess Anne d'Orleans and the Spanish Prince Carlos, HRH the Duke de Calabria, married politician's daughter, Sofia Landaluce y Melgarejo, the BabyMama of his 7 year old son, Jaime, and they had a further 4 children.
Tessy Antony was 20 when she became the BabyMama of 19 year old HRH Prince Louis of Luxembourg. When they later married, he renounced his rights to the grand ducal throne and she became Tessy de Nassau and Countess. After another son and finishing her education in 2009, the ex-military got promoted to HRH Princess Tessy. Louis's paternal uncle, Prince Jean, similarly renounced, married his BabyMama, but he and French juriste Helene Vestur dlivorced.