The employment questionnaire of general enterprises will have a column of marital status, so that employees can fill in whether they are married or not and their marital status. If you are promoted in a state-owned enterprise, you will face political review when you join the party, and your marital status and family situation will be investigated in detail.
Now even if you enter other ordinary private enterprises, there will be information to fill in whether you are married or not. For some enterprises, married people are more stable.