Honestly, her behavior has me worried. Whether or not she was intending on reading those messages, though it's questionable whether the two of them are dating, she has a right to question him on who the other girl was, but instead of that, she's going more aggressive on the intimacy than usual. Part of me guesses she doesn't want to lose to this other girl, but that would mean she does have a thing for MC, but she may turn that answer down if questioned.
Especially with how the woman phrased that one line:
I could think of 2 perspectives from this quote. One is probably from a woman's side of thinking, "Awww, she wants to make sweet memories with him," or something along those lines.
Men, on the other hand, like MC or myself, would be confused as to why FMC even phrased it that way all of a sudden. Like what MC was thinking, it's as if she's going to leave for whatever reason, and she wants to leave some memory of her ingrained in him, in his psyche. Whether that would be a good or bad memory would depend on what happens from the next day onward.
If FMC ghosted him and started seeing someone else without even mentioning anything to him, then that will leave the MC totally confused and in a state of doubt, recalling that night with as much detail as possible to see what went wrong, warping his memories to be negative as he tries filling the holes with negative intentions, to the point that it will become traumatic than nostalgic. He would never believe another woman's advances on him again by that point, because they could be like FMC. Knowing how sadistically manipulative she was intended to be in the previous version, it wouldn't be wrong to say this response is what she's going for, whether to chain him to her for good or make him miserable, it could be anyone's guess by that point, because women can be just that passive-aggressive.
