Can the gov change a visa to partner?

Edit to add: been together 2 years, see each other all the time, met his family and friends, attend work events with each other etc Just social media he doesn’t indicate a relationship

Hello,

I am born and raised in Australia. My partner has been here 5 years and is on a student visa, they are due to finish their study July 2025. My partner won’t go overly public with the relationship because they are saying the government may change the visa to a partner visa, is this true? Is this possible or am I being fooled?

We are public in shopping centres, friend groups, family but not on social media’s or certain groups of people. Where can I find the restrictions of the relationship?

Is my partner married in their home country lol 🤦🏻‍♀️