Me [27 M] with my girlfriend [26 F] 3 months, potential breakup due to my interest in pegging

My girlfriend and I have known each other about 3 months, and we live in San Francisco, and are both highly educated professionals.

We get along -very- well, except for potential sexual compatibility. We have both never dated anyone with whom we experienced such a strong connection.

I am very sexually liberal and have no judgements about anything, she is a virgin and quite conservative about sex, and thinks she will be very vanilla. Soon after we met each other she said she would need to wait for several months before having sex, to which I agreed because we have a very strong connection and I think she is worth it. There is a religious element to her beliefs, but it's an eastern religion, not christianity.

I mentioned during a discussion about what is 'ok' in the bedroom that I wouldn't mind being pegged. This is basically the kinkiest thing I would ever try. In addition to that, I am interested in the typical range of sex acts like blowjobs, doggy, anal, etc, but think I can live without them. I assert that it's relatively common for couples to not sync up on this.

She reacted extremely poorly and wants to end the relationship because she thinks it's evidence we are not sexually compatible (mostly because of the pegging), despite my interest being very slight and I am perfectly happy to never explore it. We have discussed it at great length over many hours now.

I have a few questions:

• How perverse and uncommon is an interest in pegging for a white heterosexual male in America, on a scale of 1-10
• Is it reasonable for her to have such a negative reaction and want to end the relationship based on my slight interest in pegging
• She thinks I will very likely grow resentful because she is preventing me from exploring that part (and other parts) of my sexuality, because I'm still relatively inexperienced. I don't think I will grow resentful. Will I?
• How common is it for relationships to endure this extent of difference in sexual adventurousness

I plan to show her this thread, so please be objective.

I invite other comments and requests for more information.

tl;dr: I'm sexually liberal, she is sexually conservative and a virgin. I mentioned I wouldn't mind being pegged, but I'm fine never doing it. She wants to end the relationship because of it. Is it reasonable or is she overreacting?