there had been that one occasion when she had knocked on their door to ask for his advice about a dripping pipe she had discovered beneath the sink in her bathroom : of course it was probably all innocent enough , there had been a small leak which he had been able to mend without any great exertion , but he had been alone in the apartment that day , his wife having taken joo-hee to visit her mother in the country , and it was possible that eun-hae had waited for just such an occasion in order to get him to herself .