Lost Desire

I’ve been with Sarah for seven years now, and we started seeing each other when I was 25. We used to have incredible sex all the time, but lately, nothing feels right anymore. Last night, we barely even touched, I tried to initiate something, but she just rolled over and went back to sleep. It’s like she doesn’t want me at all. Is this normal? Do relationships fade into this kind of quiet nothingness after so long together? I feel so alone in our bed now.