bf has no sexual fantasies?

I ask my bf a lot what he wants to try in bed, what his fantasies are, etc. He says he has no fantasies and when I ask if he wants to try a certain thing he just says "I don't know." We have sex 2ish times a week and it's usually good but really vanilla and I've been getting really bored lately. I've been trying to spice things up and he kind of just isn't putting in any noticeable effort. Is this weird? I just don't know what to think. I've never met anyone with NO sex fantasies.