Is it obligatory to perform ghusl if unknown fluids are discharged upon touching the fiancé, even if this occurs in front of everyone?

What is discharged is usually either madhy (pre-seminal fluid) or maniyy (semen). To distinguish between them, please refer to Fatwa No. 39996. If the legal marriage contract has been concluded, he is permitted to touch her. However, if it is merely an engagement, it is not permissible. For more information, please refer to Fatwa No. 36940.