My boyfriend doesn't seem attracted to me anymore

We've been together for almost a year now, and it's been great. We get along almost all the time, we have fun, and we love each other. The only problem is that he doesn't seem to be sexually attracted to me anymore. We haven't done anything sexual in over a month now, and he doesn't even wanna make out with me or anything. How could I bring this up to him in a way that won't damage the relationship? Thanks!