Secretly fucking her best friend when her husband is next to her

After a long time without seeing each other, a group of four close friends went to soak in a hot spring. The purpose of this trip was to have an affair; a couple who were already married secretly engaged in a relationship with each other, and this was the best opportunity for them to be together. To keep those around them in the dark, after getting drunk, they sought each other out in the bathroom and had relations all night long. Later, this girlfriend became pregnant, and it is very likely that her husband is raising someone else's child.