Am I obligated to enjoin good and forbid evil if I see a male and female student intermingling and alone in the street at night?

The mixing of genders in universities is a dangerous evil, and its denouncement is obligatory upon every Muslim according to their ability. If a Muslim does not fear temptation or harm, it is incumbent upon them to forbid this evil using the best method, such as good admonition and gentleness in counsel. One can also communicate with the responsible authorities if they are helpful in such cases.