AITA for changing the Wi-Fi password after my roommate gave it to our upstairs neighbor?

The first clue was a television named “DENISE-BEDROOM” appearing on our router list.

I asked my roommate Leo whether he knew anyone named Denise. He said she lived upstairs. Her internet had been disconnected during a billing dispute, so he gave her our password “for a couple of days.”

I was annoyed but agreed to the weekend. Denise works from home, and losing service on Friday had apparently left her scrambling. By Tuesday, her television, laptop, phone and a game console were still connected. Our video calls had begun freezing.

I asked Leo to tell her the favor was over. He said her provider had scheduled a visit for Thursday and asked me not to be petty over two more days.

Wednesday morning, my work presentation froze twice. I logged into the router, changed the password and reconnected our devices. I did not warn Leo or Denise first.

At noon Denise knocked. She had been leading a training session when the connection vanished. She had to finish by phone and used most of her monthly data. Leo said I had embarrassed him and disrupted someone’s job to make a point one day before her appointment.

I said he had no right to give ongoing access to a service we pay for and no right to make me negotiate with a stranger to recover it. He offered to cover a larger share of that month’s bill, but the money was not what bothered me.

Denise’s service was restored Thursday. She has not spoken to either of us since. Leo now treats the router password like classified information, which feels less like agreement than sarcasm.

I keep defending the password change as the only boundary I controlled. I also know I chose the moment that made my boundary most expensive for her.