Roommate wants to add her boyfriend to the lease. Should I be worried?

He's been here essentially full-time for 3 months. She asked the landlord about adding him and now he's going through the application. On one hand, it feels fair if he's going to live here. On the other hand, that's a third person in a 2BR and I had zero say in choosing him. The rent would go down for both of us but something feels off.