My friend's wife is my ex-girlfriend.

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 infidelity, as a couple who were already married secretly had relations with each other, and this was the best opportunity for them to be together. To deceive those around them, after getting drunk, they sought each other out in the bathroom and spent that night together. Later, this girlfriend became pregnant, and it is very likely that her husband is raising someone else's child.
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