Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Friendship with the opposite sex may lead to staring, lustful thoughts, flirtations and seductions. That is why it is forbidden to mingle and mix freely with members of the opposite sex and develop friendship with them.
Responding to your question, Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
Zina is a grave sin in Islam
It is common knowledge that in Islam, fornication and adultery are grave sins and committing either bears serious consequences in this world and the Hereafter.
However, what is not so well known is that while declaring fornication and adultery as haram (forbidden), Islam does not merely forbid the actual deeds, but Islam also declares each and every circumstance or avenue that may lead to fornication and adultery as forbidden.
Allah says,
“Do not come near fornication, for it is indeed lewdness and an evil life-style.” (Al-Israa’ 17:32)
Explaining this, Prophet Muhammad (peace be upon him) said,
“Verily Allah has fixed the very portion of adultery which a man will indulge in, and which he of necessity must commit. The adultery of the eye is the lustful look, and the adultery of the tongue is the licentious speech, the heart desires and yearns, which the parts may or may not put into effect.” (Muslim)
He also said, “staring is one of the arrows of Satan.”
In another report, he said, “You are allowed to have the first casual look (which is unintentional), but do not continue to stare.”
The laws of Islam are from Allah, our Creator, who knows our weaknesses as well as our strengths better than we do.
Women, by nature, desire to be looked at, adored and cherished, while man is inclined to look at women. Allah, therefore, warns us against our own nature, which may lead us astray if we do not exercise caution and take the necessary safeguards.
Thus, Allah said,
“Say to the believing men to lower their gazes and guard their chastity…”
“And say to the believing women to lower their gazes and guard their chastity and not to display their charm in public.” (An-Nur 24:30-31)
Friendship with opposite sex
Keeping friendship with members of the opposite gender may lead to staring, lustful thoughts, flirtations and seductions. Although it may not always be the case, there is no way to tell when it will happen and when it will not happen.
That is why it is forbidden to mingle and mix freely with members of the opposite sex and develop friendship with them. It is all part of zina (fornication), which God and His Prophet (peace be upon him) strongly told us to abstain from.
Allah has given us laws in order to guard us against the evils inherent in our own souls. One recent study conducted about male-female interaction in the workplace concluded that one in every three women had been sexually involved with a co-worker or boss. If this is the case in a professional, business-like environment, then the potential for illicit relations in more casual contexts has much greater potential. Thus, Allah has been most gracious by not only forbidding fornication and adultery, but by also closing all doors leading to them.
Almighty Allah knows best.
Source: AsktheScholar.com