Sayyiduna al-Hasan bin Ali bin Abi Talib (may Allah be pleased with him) said that divorce is after marriage.
(b) Mubarak bin Fadalah (may Allah have mercy on him) narrates from Sayyiduna al-Hasan (may Allah be pleased with him) that a man asked Sayyiduna Ali bin Abi Talib (may Allah be pleased with him). He said: I said: "If I marry such-and-such a woman, she is divorced." Sayyiduna Ali (may Allah be pleased with him) said: "If you marry that woman, nothing is due from you."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 14883