I don't entirely understand all of the hate towards this character. She's not a psychopath just because she turned someone down and then sought them out after of their own volition, farthest thing from it. And she's not a whore, she explicitly stated that herself by telling the main character that she's a virgin and doesn't have much dating experience.
Yeah, what she did wasn't very cool of her, but she's an overly cautious person. She's willing to risk burning meat rather than get a stomach ache. As in, she's willing to risk losing a love interest until she's absolutely sure that the time is right.
And just putting yourself in her shoes, wouldn't you find it odd or a deal breaker if the person that you were romantically interested in told you that, oh, by the way, they've got a young member of the opposite sex living at home that doesn't pay rent and no, they're not blood related in the slightest. From the comments I'm seeing, it seems that if it was a woman with a young guy at home, you'd all probably find issue with it.
Also the questions she's asking NEED to be asked by someone. He doesn't have the balls to ask these questions because he's too nice. Isn't that one of the reasons that the other girls like him from work? He's nice, considerate, and caring. All of these traits means he's easily taken advantage of, especially by a young girl in need. So far she hasn't done anything outright mean or bad to her. She's just asking her simple questions, "Has he raped you?"/"Are you giving him sex in return for shelter?", and "When are you actually leaving?". Nothing outrageous so far.
So yeah, I really don't know what the problem here is. So far she's just being a normal human being with regrets and worries.