Husband is obsessed

My husband is obsessed with anal. He is constantly asking during sex to fu@k me in the ass as he puts it. He always touches me back there but does stop when I ask him to. He wants me to touch him there too. If he is having a hard time finishing he asks me to talk dirty to him about me wanting him to fu@k me in the ass. The other day during sex he even blurted out "Fu@k me in the ass!" I have tried a little bit like with his finger but it is just uncomfortable for me and I don't enjoy the feeling. I have talked to him about this but I feel like our whole sex life revolves around him obsessing over anal. Is this normal?