Does touching her husband's penis, or semen, or the fluid that exits a man before intercourse, without anything exiting from her, nullify her ablution, and is ghusl obligatory upon her, or only ablution?

A woman's ablution is invalidated if she touches her husband's penis without a barrier, according to the Shafi'i and Hanbali schools of thought. The Maliki school holds that ablution is invalidated if touching is accompanied by desire or intention, otherwise not. However, merely touching semen or pre-seminal fluid does not necessitate ablution. If the touched substance is an impurity, such as pre-seminal fluid, then the affected part of the body must be purified.