Is this weird or cultural?

When I have a guest show up at my house and I’m about to eat or am eating, I stop and resume later or offer them a plate, so we can eat together.

My aunt-in-law, with her family (they are German- adult daughter and husband) have started eating in-front of me without even offering and I felt very uncomfortable to the point I stayed out in the patio until they finish. I find this so strange and rude.