Wont leave my asshole alone

Im so sorry for the tmi in this post. My other half juat wont stop messing with my asshole during sex! Always has to be touching it or licking it etc. I dont like anal so ive told him its never happening and ive told him to stop messing with it. He listens for a cpuple of weeks but then goes back to messing with it again and then during sex i just end up getting annoyed with him (he doesnt know that tho) im in my mid 30s and i feel like if ive put a boundary in place he should listen!! Been together 2.5 years. Any advice welcome.