What is the ruling on unlawful seclusion (khalwa) in the following two cases: a girl being alone with a non-mahram man in her house with a barrier between them and speaking to him on the stairs, and a girl speaking to non-mahram men at the door of her house in the absence of her parents?

The seclusion of a man with a non-mahram woman is Islamically forbidden by scholarly consensus, based on the Prophet's (PBUH) saying: "No man should seclude himself with a woman unless there is a mahram with her." Seclusion means the gathering of a man and a woman in a place where they are safe from anyone entering upon them, or where their persons are concealed from people. Seclusion is negated by the presence of a barrier between them, or by the presence of a mahram, or a trustworthy capable woman. It is not considered seclusion in open places that people usually enter, such as a frequented mosque. Caution must be exercised regarding the gathering of a man and a non-mahram woman if there is any suspicion, even if seclusion is negated, in order to block the means to temptation.