Sex drives naturally fluctuate, often caused by age, physical and mental health, stress, medications etc.
Has there been effort made in making you feel desired and sexy? Do you masturbate in your free time? Do you orgasm during sex? Is sex exciting for you? Are you happy in your relationship? Are you under a lot of stress lately?
I highly recommend looking into resources (articles, podcasts, videos, books etc) shared by sex therapists and other professionals about this topic! It's something that most people experience at some point in their lives, and there's lots of tips and advice available.