From what you're saying it seems as if she knows about the hose but not necessarily the encasement. I suppose you could approach it slowly and tell her its a "facet" of the fetish. Some of us crossdress, some of us love feet and some of us encase ourselves! I wouldn't advise pressuring her to try it straight away but ask her to be open about her feelings on it. If she feels too uncomfortable to take it too the bedroom, don't beat yourself up over it. Life's too fucking short to worry about the little things!