I have low libido

I have been dating my fiancee for 7 years now and I fell in love with him the moment I met him and he did with me. When we first started dating our sex was mainly daily. I would even go to his house during our lunch and have sex and then go back to work. It was insane!!! it was mainly because we where at our first stages of dating. Then my sex drive slowly started to crash. I love him more then ever today. He is an insane sex machine. He can cum and keep going and keep ejaculating and keep getting hard for hours, but unfortunately I give up before he does. there is times where he wake up at night and tries to get me wet but I can't and it upsets me where I get mad at him and at my self for not being able to please him when he wants. it just kills me not being able to do that for him. I know that he says he understands, but then I see how it bothers him at times. We talk about it and we come to a solution on trying new things for me so I can get aroused and it will work until it doesn't. does anyone have advise what can i do? Or is anyone else going threw this?