I don't think it's Mayuri who gives up quickly, just her childhood friend (can't believe they are not going out, lol, he practically strips her naked a few times, and it doesn't end up a big deal for her) goes full force instantly.
I still wonder if they are in a relationship or not
Chap16 shows her coming home and taking off the thights while the guy was inside her room, maybe they're just that close...