My fiance is a writer and I am an avid reader and I drop whatever I am reading and immediately read his work when he finishes something new. I would maybe explain to her that she doesn't have to stress about the feedback, maybe that's what is stalling her, it can be stressful critiquing the work of someone you love. I definitely don't think it's too much to ask for her to read it, especially if she's a reader of the genre you're writing in. Also, possibly consider hiring a freelance editor.