@kinosseur That's not how I read the scene at all. I think you are assigning malice where there is none.
No, it's not realistic to find someone this daft, but manga characters are rarely realistic and exaggerating flaws and working on them is where a lot of character development happens in series.
Let me explain Meguro's personality/character:
She is the pure distilled essence of non-plussed(chill) + has close to zero... ego? Not that she feels no self-worth or esteem, but that what other people think of her doesn't even register on a cognitive level. Sex isn't anything special, not in a slutty way, but literally like having sex/going to the zoo/seeing a movie are all the same level of mundane itinerary. All are equal ways to spend time in her eyes and it's making her BF happy and going out with someone is about making each other happy. (Except she has zero ego so she literally has no personal demands out of the relationship)
Once the boys of the school found out there was this girl who never said No to anything, they all started taking advantage of that to get laid. But once they lost their virginity and they got bored, they'd dump her. It says way more about how fucking rotten the boys were than anything about her, because obviously she's not right in the head on some level to be that passive. So I'm sure a bunch of them came up with all sorts of feigned date ideas then thought they were being sly getting her to go to the love hotel instead. Hence why she was like "Oh, you were serious." She accepts as matter-of-fact that literally every previous boyfriend was that way and that was just how relationships were.
In a way she feels like some Machine Learning AI terminal. Her only frame of reference for dating is it's about boys asking you to have sex, and lacking any other data points... well okay then. Anything you say to her that isn't a direct question or involves clarifying something about someone else, she just lets it go right in one ear and out the other without firing a single neuron.