Am I the problem?

Throughout my life I have been very sheltered from anything sexual or sex related. My parents never even talked about the birds and the bees I had to be one of the kids who learned from their friends or tv however I have never been able to reach the big O. Thankfully My husband and I have always had a very healthy sex life and relationship but I do not feel like he is happy or fulfilled sometimes. He always assures me he is satisfied and happy and loves me but I know that he really need the assurance of a good job by getting the big O from me.😔 I'm not sure what to do and he cracks jokes to let me know its not a big deal but I feel like I'm letting him down sometimes