I don't care too much whether you translate the 外来語 gairaigo ワーキングホリデー as Waakingu Horidee or Working Holiday or whatever, but 住んでいる is definitely "sundeiru" not "sumundeiru."
Just like what @ MUGENNO SHINDO said what's the story?
According to http://www.dlsite.com/ecchi-eng/work/=/product_id/RE173687.html
Ayane was on a working holiday visa. Her boyfriend Hiroya had some time off and went to visit her, but was shocked to learn she was in another relationship with her roommate Neil.
Even learning about the details of their affair, even watching Ayane and Neil together, Hiroya couldn't bring himself to dump his girlfriend.