It's not rational, it's not something I have control over. It's something I deal with and largely have built techniques to try and lower the stress of.
I'm aware this is fundamentally a "your brain is wired different" issue, and so I'm never sure what the etiquette should be on asking others to chew with the mouths closed.
Many cultures don't have any concerns around slurping/chewing with mouth open, so meal times in mixed company are often quite hard for me. Add on the stress of trying to figure out whether I should even mention something (and make everyone else uncomfortable) is bonus stress on top.