Is it ever Okay to steal?

So my cousins have a ps3. They have a certain game that you can only use to play online. Their mom wont let them play online because she says it causes the computer to get viruses. I know it doesnt but theres no convincing her. Anyway, that game just sits there, it will never be played. My brother one day asked if he could borrow it. My cousin, hes the type to always tell his mom where hes going. Or always asks if he can do something. So he said to ask his mom if he could borrow it. He asked, she laughed and said he has to ask her husband. Her husband is in prison for the next 12 years. Thats kind of rediculous to me, her saying that. Well i was looking through my stuff the other day and i saw that game. I knew he took it. I know hell return it secretly thats how he is. But is he wrong in doing so? Like i said theyll never use it itll be forgotten. The only time theyd remember it is if it gpt brought up. And the husband wont get mad why would he lose sleep over that while in prison. Also, out prs3 was broken so we let them use certain accesories for their ps3. We left them there pretty much so they could always use them and my bros mad that they cant return the favor.