A couple pose for pictures after registering for marriage at a marriage registration office in Wuxi, East China's Jiangsu province, Nov 11, 2015, or the "Singles Day" called by many netizens and young people. Many young people chose to register for marriage on the "Singles Day" to bid farewell to their bachelorhood. [Photo/Xinhua]

Wang Changshou, head of the Shaanxi Academy of Social Sciences, said it is necessary to strengthen moral education surrounding marriage, but it is not appropriate to ask students to sign a promise.

He said it is not fair to only open the class for female students because relationships and marriage involve two people. Male students should also be educated, he said.

"It is an obsolete concept to curtail only women's behavior, but not men's," he said.

"It is correct to stay loyal in marriage, but sex before marriage should not be prohibited," Wang said.

Sun Shan, an associate professor at Northwest University of Political Science and Law in Xi'an, said even though the students signed the promise, it doesn't have any legal force because loyalty starts after a marriage is established.

"Whether a woman has had sex before marriage or not is private and protected by law, and no one has the right to know," he said.