Need advice...!

Hi everything. I need a bit of advice. My partner seems to think that when I’m on my period and we can’t have sex (neither of us want to when I’m on my period which is fine), he thinks I ‘owe’ him a blowjob. He says it every month. Some times joking but I know he means it really. I’ve told him that with periods I also get pain, tiredness, moodyness and just feel like general shite but he doesn’t seem to understand. It’s like talking to a brick wall. Am I being unreasonable?