Difference in sex drive

My husband and I have been together 6 years and when we first got together our sex drives were similar but over the years the gap has grown. If given the choice I'd want to have sex 4-5 times a week and he would choose maybe once a week. He's rarely interested and it's causing problems. He's going to get tested to see if something's causing it, but I can't help but think about what if there's nothing causing it and this is just the way it is. How can I spend the rest of my life feeling insecure because he never wants me?

He's 28