I think he can't make you happy, because you don't allow him to,... And the only way to allow him to make you happy is to open yourself to him.

Speak about what's really going on in your mind, your troubles, fears, confusions. He may not be able to solve them, but at least he can comfort you and share the load with you. The way you are behaving now builds a wall between both of you, where lies, misunderstandings are allowed to accumulate.

Don't fake orgasms. Just say that you were not feeling like it, speak about your emotions. I understand your misgivings about marriage: if you can't share your mind with someone so intimate to you, you are burying yourself alive.

So gather your courage and be more open to him. Since he does ask you questions, he seems to care about you, and it's a pity that you don't give him a real chance to help you.

As for the wedding angst, it's very normal, me and my wife went through the same thing. The time running up to the wedding is where many people really start to seriously think about their relationship (of course, it should have been done before, but that's life, and better late than never).

Also, a wedding implies a lot of stress and cooperative work within the couple, which can generate friction. So doubts and questionings are very common. They should not be suppressed, but used as chances to really deal with problems and deepen the relationship.

A couple goes through many difficulties with time. A problem ignored will remain a stone in your shoes, and eventually cause a much more painful sore. If dealt appropriately, it can reinforce your relationship. After all, you become more confident, when you realize that you can manage difficulties with your partner.