MIX GATHERING IS STRICTLY PROHIBITED IN ISLAM.

There are some rules to be strictly followed by a Muslim. Firstly looking a ‘Non Mehram’ is Haram in Islam except from the first unintended sight.

Jareer ibn ‘Abdullah [may Allah be pleased with him] said: “I asked the Messenger of Allah [P.B.U.H] about an accidental glance at a woman. He commanded me to turn my gaze
away.” [Al-Tirmidhi]

The Messenger of Allah [P.B.U.H] said: “O Ali [his cousin], do not follow a glance with another, for you will be forgiven for the first, but not for the second.” [Al-Tirmidhi: 2701]

Then mix gathering is strictly prohibited in Islam.

Islam orders both men and women to lower their gaze while they are in public places.