I'm more sex driven than him...

My SO and I have been sexually active for almost a year now and his sex drive is continually decreasing. It's gotten to the point where he literally says no when I ask him sometimes. I love him more than anything in the world but I feel like he's getting bored with me and like maybe I'm not enough to keep his sexual desires at a maximum. What should I do? We're not into kinky stuff (okay he's not.....) so just something reasonable. Thanks in advance!