I say, and with God's success: It is permissible for a man, when he has sexual relations with his wife, to approach another woman and have relations with her before he performs ablution; as narrated by the Mother of the Believers, Aisha, may Allah be pleased with her, who said: "I used to perfume the Messenger of Allah (peace be upon him) and he would visit his wives, then he would become a pilgrim in the morning, still smelling of perfume." (Bukhari 267). As for performing ablution between sexual encounters, it is recommended; as narrated by Muslim (308) from Saeed Al-Khudri, may Allah be pleased with him, who said that the Prophet (peace be upon him) said: "When one of you comes to his family and then wants to return, let him perform ablution between them." Al-Hakim added (1/254): "For it is more invigorating for returning." And Allah knows best.