I used to feel that way too, and always felt pressured to orgasm so as not to make the guy feel bad. Or at least pressured to finish quickly. Maybe if you feel comfortable, you could try talking to him about it. If he knows it might take you longer to orgasm, maybe you'll be put at ease knowing that he isn't expecting it to happen within a couple minutes. Somehow I was able to get my thoughts off of the performance anxiety, and was finally able to orgasm with a guy even though I never have before. So it is possible!