Let's try another scenario- Sara goes out on a first date with a guy. They talk beforehand and decide to have dinner out and then drinks back at her place. He takes her to a restaurant and buys her a nice dinner. He then takes her home, and goes up to her apartment for drinks. They have a nightcap and chat for a bit before he finally says "Okay, I'm ready now." Sara says "Ready for what?" to which her date replies "Well, the sex of course! Aren't you going to sleep with me?" He and Sara had never discussed having sex with each other, but he believes that sex on a date (especially after he has paid for dinner) is an "unspoken given," and thinks that it's very rude of Sara to have gone on a date knowing that she wasn't going to sleep with him afterwards.
Obviously, this would totally and completely not fly. So why is it okay for Sara to do the exact same thing only with a meal instead of sex?