I’m never horny ... like ever ?!?!

So this has been happened about a year. I’ve been with my boyfriend a little over 3 years now and things are better than they have ever been. But I’m never ever in the mood it’s awful, I feel bad be he’s always in the mood and he seems to be frustrated. We have sex once in a while but I mostly just do it for him. What’s wrong with me ? I’m 35 and healthy he’s 31. I’m physically and emotionally so attracted to him. Help !