it sounds like you've got an automation that says "at 9pm turn off the dining room"
if you sit down at 8:45, it will go off halfway though dinner.
If you get the Eve app, you can add conditions to triggers. (
App link)
The app works for all homekit devices, you don't need any eve devices. It's just a second front end to the home app, and has more options.
One way I've worked around stuff like this is using the actual value as a "lock"
although I've not done it in homekit / Eve.
What I mean by "lock" is I'll set a light to 98% instead of 100.
you'll probably not notice a difference in lighting levels in the room
you can then set a condition on the automation so it won't trigger if the dining room is at 98%
You could make a "dinner" scene that would set the light to your "locked" level.
you could also use a light (or any other homekit device) elsewhere as the lock, so when you play the dinner scene, it will also turn the kitchen off. and then the automation will not trigger when the kitchen is off
you could also get a motion sensor, as suggested above, and set the automation to "at 9pm if motion is off". although that could also be a bit hit or miss, since eating dinner normally doesn't involve a lot of big motions to trigger the sensor.