From wisebrother.com:
TikTok is obsessed with a new term right now called "boyfriend air." But it's not just about smelling bad.
Women are claiming the air in their boyfriends' apartments is so gross, it can mess with their hair, and even their make-up.
One woman who stayed with her boyfriend recently said she'd shower at night, but feel gross the next morning anyway. Her hair was greasy, and her make-up would easily rub off.