If they can't or won't engage with the topic at all — they deflect, freeze, change the subject — that isn't a problem to solve by asking better. You can still keep your side of it: no pressure, no re-asking, and no working the topic in sideways through wordless touching during sex. A conversation takes two willing people; your boundaries only take one.
This isn't all-or-nothing. Anal exists as a ladder — talking and fantasy, external touch, more — and every rung, including the bottom one, is a legitimate permanent home for it. "We only ever talk about it" is a destination, not a failure. And whatever rung you're on, pain means stop and regroup — never push through with more patience.
Direct talk isn't the only respectable format. Shorter, later, or written down are all real ways to have this — especially if either of you finds explicit sexual conversation hard. And direct, out-loud asking isn't the norm everywhere; it's one path, not a universal correct one.
One honest caveat: this article is about the asking layer. Even asked perfectly, a request built around one specific act carries its own gravity — the practices here reduce that pull, they don't erase it. If you notice the pull winning, that's what the red flags earlier in this article are for.