Perhaps it was because the merchandise was pretty pricey for this demographic. Sure A&F clothes are on the pricey side too, but teens have parents to buy their clothes. Most 22-35 year olds don't have mom and dad purchasing their clothes and because they are trying to establish a life on their own they can't afford the garb.
Or maybe it's because the brand was lacking a solid identity. To me Ruehl really didn't make its mark and didn't come out strong. Personally I didn't think it had clear brand definition and came across a little to aloof. To me it seemed to never make a connection with it's potential customers therefore never establishing a loyal following.
Be on he lookout for a possible going out of business sale. Even with the potential good deals it's very sad to see another business close it's door and more people out of work.