it wouldn't make me feel 'weird.' I understand sometimes you just need a woman's touch - I would even encourage her to sleep with other women, as long as it didn't infringe upon our sex life. Perhaps it's me being oblivious, or maybe it's just some supreme sense of sexual confidence, but I know that the one thing I can not do in bed is be a woman. So, if that's what she needs, she should feel free to seek it out. I strongly prefer that over her being sexually frustrated because of something I am incapable of providing.
Of course, if there is anything cock-related she wants, I should be the only option she considers.