If there is sexual relationship between hotel employees, is it the hotel's responsibility for the derailed husband to blame the hotel?

You can't blame the hotel. The hotel has no responsibility, because the hotel can't restrict the behavior of employees after work, and you can't do anything that doesn't conform to the hotel employee system during working hours. As for your hotel staff having sex with others, it is the moral behavior and privacy of this person, which is not within the hotel's restrictions, so the hotel is not responsible.