I went thru this same issue not too long ago, and I thought that since I cared about him so much that the fact that he couldnt please me sexually wouldnt matter , but eventually it did!!! I couldnt get over it and look past it, we tried so many things, I didnt want to hurt him by telling him that he couldnt make me feel good at all, so I kept it to myself until the oppurtunity presented itself to tell and he was ok with it because I expressed this in a nice, non-ego bruising way and we went from there. In the end, we arent even talking and dont have any contact anymore and the sex never got better even after we had the talk. I dont think it was him not knowing how to do it or what to do I feel it was just that he personally couldnt get me off and make me feel good, no matter what we tried it was never good!!! I know I could get off because a past boyfriend made me feel great, but this man, no matter how much I cared for him and wanted the sex to be good it just wasnt cutting it!!!
Im not saying to dump him or that sex is the most important thing because it certainly is not, it is great and important in a relationship to have great sex with the person that you love and are commited to, but should not be put first!!! Relationships that are based on sex or sex being of high importance will eventually fail and get old/boring, because so many things have to come first in a relationship before sex can really be as wonderful as God intended it to be.
If you want things to work with this man, then you have to work at it TOGETHER!!! That is the key here, it has to be a concerted effort on both your parts. You have to speak up and let him know...when he gets to a spot that you are feeling it great moan loader or say something encouraging like" baby it feels so good right there" this way here you arent making him feel bad you are letting him know what he is doing right and good and making him feel good also so he will keep doing what he hears you say is good and makes you feel best!!! I hope this helps!!!
Best wishes with this all!!!!