You should respect someone's food choices.
Olivia is a vegan who is friends with Megan, a omnivore.
Olivia wants to have lunch with Megan.
Olivia has lunch with Megan and respects her food choices the same way Megan respects hers.
Olivia gives Megan a lecture on why you shouldn't eat meat after she orders a steak salad.
Olivia and Megan continue to lunch together despite their difference in food preferences.
Not wanting to be lectured for her food choices, Megan never has lunch with Olivia again.