My boyfriend cannot cum in my ass

¯\_(ツ)_/¯The title is very simple and clear: my boyfriend cannot cum while fucking me. We've no problem orally or with hand or toys etc. But when it comes to cream pie, he cannot cum..he says he's never cum into someone's ass and it doesn't feel the same..the advantage of this is that we can have anal sex for hours! I wonder if you guys have any tips and tricks that I can use to make him cum 🤔