Girls refusing to move in with a guy without a ring

[trapsetter]

I am attempting to advise a good friend on a developing relationship he is having with a girl he's crazy about. They currently spend about 5-6 nights per week together but have separate places. They both are talking very seriously about moving in together. The difference of opinion however lies in the issue of being engaged. While my friend definitely foresees marrying this girl if things continue to progress at the rate they have (they've been together a little under a year), he's not sure he wants to go out and buy a ring just now. She, on the other hand, has said there is no rush to get engaged, but that she won't move in under any circumstances if they are not engaged.

OOT's thoughts on this? Clearly he has to respect her wishes, but is she being unreasonable?