I struggle with this too. I believe that being circumcised makes the issue worse but it's difficult to know that for sure since most of us have always only experienced it one way.
For me, the only things I have found to work are to not let things get too wet (don't use any lube, or if you do use it, don't use too much), to never masturbate EVER if you are dating and regularly having sex, and to NEVER watch porn. Oh and if it helps to fantasize about anything that turns you on while you're having sex with her, by all means do it. Could be memories of past sex with her or other women, fantasies about what you'd like to do, or whatever.
I also found that it took me a while to figure out what physical characteristics most turned me on. I have no idea if other guys went through the same experience I did in this regard, but I had to literally date a lot of different looking women before I could actually consciously identify, define, and put to words specific things that turned me on and things that turned me off. For me it was much more detailed than just: is she fat or skinny, hot or not. There were some women who just didn't turn me on that much even if they were objectively attractive. So you might need to be completely honest with yourself about how much this girl truly turns you on.
And some women are just better in bed than others - the way they move, the sounds they make, the things they say, how out of breath and turned on they area, how much they shake and tremble, how crazed the look in their eyes is, how often they orgasm and how quickly it happens, and how much you feel they are acting vs being genuine. It's all very individual. Another thing I have noticed is that while having sex, you can mostly focus on her pleasure, mostly focus on your own pleasure, or try to focus on pleasure together at the same time. Don't get me wrong, it ALL feels GOOD, but not everything will always all allow me to finish. The mutual focus has only allowed me to finish with very few women who were really sexually curious and into stuff like Tantra. So I will tend to focus on her for a while until I've gotten her off once or twice (or more depending on how easy it was) and then shift to focus on myself to finish, without trying to concern myself with whether what I'm doing is providing her the best possible sensation. Sometimes you might get in your head while doing this - thinking she doesn't like it, and that can make it harder for you to finish, and sometimes the cause of you getting into your head is that she isn't doing a good job conveying pleasure to you while you are focusing on yourself. If she's just laying there like a dead fish while you pound away, that may not have a positive affect on you. If that is the case, you can talk with her about it but in doing so you run the risk of then knowing that she's probably just "acting" because you told her to which won't help either. So it just comes back to the fact that some women are better and more sexually compatible with you than others, and some women's bodies just turn you on more than others.
Lastly, your level of attraction to a girl overall, all things considered including personality and how much you value, admire, and respect her, play a huge part too. The best sex I ever had, which I still fantasize about to this day, was with a girl a lot of guys probably would say wasn't that attractive. Her face was decent to me but her body, for me personally, was incredible and she was an elite athlete. Aside from just being really, really good in bed, I allowed myself to become far more enamored with her than I should have been, partially due to her athletic accomplishments and partially due to her aloofness and inability to be "caught." Wasn't a healthy situation for me but man did it ever make the sex incredible. I'm not suggestion you make the same mistake I did - just demonstrating that the more you admire and respect a girl, the better the sex can be.
