I think probably a lot of the women who say they don't like anal have been put off by some guy trying to slam his cock in their ass without much preparation. It's a shame because it can be very enjoyable if you are introduced gently.I've always found that proper gentle attention to my lovers little bottoms leads to success, and I've been successful nearly 100% of my attempts. As far as I can tell, too many guys just try a little spit and go for it. Rarely ends well. Gentle massaging (while kissing or doing oral on her pussy), a little rimming, and pretty soon they are moaning and ready. Some will ask for it directly. Others will be pushing their little butts in the air but don't want to come across as nasty sluts so won't ask. In those cases, go for it but be gentle and use lots of lube. Sloppy seconds works great. If not available, use KY or Astroglide. Slip and slide a little on her bum. Pretty soon she'll be pushing back against you and the head will start to enter. If she's a regular, it will slide right in and you can proceed pretty easily. If she's a beginner, take it slow. Push gently and let her adjust. You WILL be rewarded. Once she is comfortable, her bum will relax and you can go at a rate she can handle. Treat her gently though if you ever hope for a return. Let her dictate the pace.
Maybe the problem is that some guys first intro to anal is from watching porn and they forget that porn actresses are used to getting their asses fucked regularly and so assume that any woman can go from zero to getting their ass pounded in one go. It just isn't going to happen.
Like most things it gets easier with practise and I love having my ass fucked hard but that's only because I'm used to it regularly. If my first experience had been some guy who had no idea trying to ram my ass, I think I might have been put off too xx