Is "romkamerat" only used when talking about someone you share a room with, or is it more like the American usage of "room-mate", which seems to be used even if they have separate bedrooms, but share a flat or house ("a flat/house-mate" in British English)
Sharing a house with someone (separate bedrooms or not) I would use 'samboer', but maybe it's different in other parts of Norway? Romkamerat for me is more something in a student setting, whilst samboer is used when you're living together with one or two other people in an apartment/house together. Anyone that can confirm this? :-)
That's correct, romkamerat is in a student setting. While samboer is two people living together in a house or an apartment.
My understanding of 'samboer' is that it's usually used to signify two people who are in a romantic relationship and living together. Is there a word for someone you share a house/apartment with, but who is just a friend?
Any reason why this could not be "... his roommate"? E.g. she visits a (male) friend, and she does not like his roommates
"Sin" points back to the subject, "hun", which is female.
Your sentence would be the translation of "Hun liker ikke romkameraten hans."