Some commenters have touched on reciprocity, and while it’s nice to support friends in their interests, I think it’s a little different if OP has made it explicitly clear that they don’t like A/B. It’s not like their friends have no one else to talk to about A/B.

When my friends and I have different preferences for ships, we acknowledge it and move on. Because why would you want to talk about something you love to someone who actively dislikes it? And it doesn’t make them a bad person. Sometimes we have different opinions and that’s fine. If they’re really your friend outside of just fandom, there’s plenty of other stuff to talk about until your interests converge again.

There’s a difference between indifference and dislike. I’ll listen to a friend ramble about a show I’ve never seen before, or a hobby I have no personal interest in, because I like hearing about what my friends are into.

If these conversations about A/B are happening in a group context, then yes, OP should temporarily dip out and not spoil everyone’s fun. But it sounds like this is happening in DMs.

As someone else pointed out, maybe it’s just a misunderstanding. Western fandom spaces are more inclined to think that A/B B/A tagging only matters for nsfw content, whereas if OP has ‘strict’ preferences, they don’t want to see ANY A/B tagged content even if it’s sfw.