Is Friendship Between Opposite Sex Prohibited?
Merely calling a boy one’s brother does not maker him one, but it does create a sort of implied barrier between two parties to extra intimacy. However, this does not mean that frankness with that boy should be of the same level as with one’s biological brother. Only that kind of interaction is allowed where norms of gender interaction as mentioned in Quran can be observed properly ( Please see : Discussion 30301 ). It is more likely than not that a boy and girl talking in that way would at some point deviate from those norms, so a conscious muslim should be highly cautious about such interactions. There is no prohibition in interacting with the opposite gender as long as one is observing norms of gender interaction as mentioned in Quran, is mindful of the sensitivity of Islam towards adultery and taking appropriate measures to counter any pitfall in this regard. Hadith prohibiting a boy and a girl to sit alone also belongs to the same preventive domain. Since this is a slippery slope that is why great emphasis is given to the precautionary measures as well. Please also refer to the videos in the following thread : Discussion 84224