Getting a Roommate Landlord Raising Rent?

[beachvibes]

What is the name of your state (only U.S. law)? St. Lucie County, FL

I moved into a 2 bed 2 bath with the sole intention of looking for a roommate to help out with rent and expenses.
I informed the property manager that I am close to finding a suitable roommate and they informed me the owner of the condo wants an extra $100 a month?
Is this even legal because this came out of nowhere and I feel like I am getting taken advantage of?

 

[FarmerJ]

What does your written lease say ? If your a month to month renter you can simply tell this LL `NO` with a proper notice that you will be moving. If your on a fixed term lease does it allow you to sublet to a roomate and does it have language that allows for the rent to increase ?