It's rude to unset your partner's alarms.
James lives with his girlfriend and has the day off while his girlfriend has work.
James wants to sleep in late.
James sleeps on the couch, so he won't be bothered by his girlfriend getting ready early.
James turns off his girlfriend's alarm so it won't bother him.
James' girlfriend can get to work on time without disturbing him.
James' girlfriend is late for work and gets in trouble.