Sexual Frustration

Lately I have been getting very upset after sex if I don't recieve an orgasm. I have a hard time talking to my boyfriend about it so I usually just get quiet and pout and it probably shows. I can't reach orgasm from penetration sex. And I haven't told my boyfriend of one year. He thinks it's just "hard for  me." But he doesn't know that It's never happened to me ever!! Sometimes he is very good about making sure I come, other times it's just like okay we had sex, I came, let's move on. I'm afraid to talk to him and I don't know why. I'm starting to resent him and get really angry but I know it's probably my fault for not taking to him and telling him what I like.