Basically, the mc transmigrates into different worlds and has to be good partners to the different cannon fodder characters. In one of the worlds he becomes the son of some kind of high official in accident times. His mother wants him to marry his cousin but he says no because his mission ways to protect his real fiancé. Anyways, the mom forces him to take the cousin as a concubine but he basically leaves her out to dry. I've been trying to find this book for sooooo long. Please Help!!.