Monokage no Iris doesn't end at that point, the MC goes to the abandoned building again and the husband finds him there. From what I understood from the raws it seems the husband takes him home and has sex with his wife in front of the MC, but it backfires and she ends up having sex with MC and going away with him. The ending wasn't so clear (since it is hasn't been translated yet) but they're travelling somewhere by train and the she gets off without telling him. They exchange some words and the train leaves the station