I agree with Jenna. Sexually speaking, most people who aren't interested in some act are not going to be talked into it, and if for some reason they are, they go into the act with negative emotions and it turns out to be just as bad as they expected. What do you get? Resentment. Trust me, it won't be worth it. Anal sex isn't something you can go into with a negative mindset, which it sounds like your s/o has.

Maybe a better way to go about things is to ask her what bothers her about it, and then research it together. Knowing that others have gone that route before and enjoyed it might make her feel a bit more comfortable. But if she feels pressured, it will probably just make her angry and more against the idea than she was when you started. Good luck

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I am certain of nothing but the holiness of the heart's affections and the truth of imagination. What the imagination seizes as beauty must be truth - whether it existed before or not.
-John Keats