See, Van Lente can't win. Reasonable explanation? Well, you should have been more clear. The truth is, I thought they had sex when I read it. Furthermore, I didn't get the implication of it until it was mentioned here. But, even before Van Lente clarified, I was willing to wait to see what happened next. Because it's serialized fiction. Mis-directing your audience (even if it's unintentional, as this was) is part of the bag of tricks.
Well, IMO, Van Lente should have made it clear within the story that there was no sex between Michelle and the Chameleon rather rather then having to explain it, which to me is just bad storytelling. Also, even prior to this, Van Lente and Marvel let the whole thing continue to be seen that way until, after issue #604 came out, someone finally asked him about it (and remember his initial response was that, while he believed rape didn't take place, what the Chameleon did was a "horrible, evil, reprehensible" act before coming out AGAIN and saying there was "no sex, and therefore no rape." And given how Marvel's "all ages" comics usually don't actually show any characters doing the deed and even when they show two people naked in bed, the word sex isn't even mentioned, it certainly leaves enough room to think something happened. After all, a lot of people believe Peter and MJ had sex at the end of issue #149 and that Peter and Betty had a one-night stand in issue #189, even though there was no actual depictions of the acts themselves. So it's not hard to make such an assumption, especially when it's left intentionally vague (and it this case it certainly was more than suggestive).
And you're completely dismissing the fact that her encounter with Chameleon/Pete wasn't the first. This isn't the case of someone going gaga after one little peck on the cheek. The two of them were living together, slept together, and then fought about it. The reason they fought about it wasn't because Pete blurted out that he didn't remember, which obviously, Michelle did. Which means to me that it was more meaningful to her than Pete. Now, she's all ready to dump Pete out of the apartment, and Chameleon/Pete puts the moves on her. Which indicates to Michelle that maybe it meant more to him than he first indicated. So to her, Game On again. Her reaction, although a little over the top, is perfectly reasonable.
This is no different than any "romantic farce" except with a supervillain twist on it.
I was exclusively referring towards Michelle and Chameleon being on the kitchen floor, but yes, I do agree that, for the most part, Michelle's reaction towards Peter after their drunken hook-up was understandable, even though in that case there were also moments where she went over-the-top in that she said he was the reason there were "waiting periods for handguns" and that whole business with leaving out the cookies and padlocking the fridge as a form of revenge and another message she wanted him to leave the apartment. And I agree that, in light of what happened with the Chameleon, she would think that Peter would want their relationship to be more than a drunken one-night stand as it seemed to confirm he felt about her the same way she apparently did him.
HOWEVER, what I am saying is that if there was no sex between Michelle and the Chameleon, look at how she REACTS to what is apparently a mere "make-out session" where no sexual intercourse took place. She starts doodling "Michelle Parker" in her notepad; she greets Peter with a kiss and calls him sexy; she starts making demands like him being on time, how long they must have "quality time" together, what time they must go to bed and snuggle; she gives away all of his clothes to the goodwill and plans to take him shopping for new ones; and she arranges them to have a date to meet her parents.
See what I'm getting at? In one case--learning that Peter can't remember them having sex because he was blackout drunk--her reaction, while over-the-top, is at least plausible. In the other case--her believing she and Peter made out on the kitchen floor but didn't actually "go all the way"--she's all but ready to drag him to the altar. I realize that Mark Waid and Van Lente are trying to indicate that Michelle grows in infatuation for Peter based upon those two instances as part of a "romantic farce," but, ironically, if she and the Chameleon did actually have sex, her behavior towards Peter, while over-the-top, is, just like her behavior after the drunken hook-up, is plausible. But if no sex took place, then her behavior is just comes across as incredibly extreme.
Now don't get me wrong, I not saying that I prefer if Michelle and the Chameleon having sex, mind you, but I'm just saying, if read that if they did, it's more plausible although certainly very squicky. Not to mention, I'm starting to think that, while Van Lente is saying there was no sex, there's enough suggestiveness in the actual comic to suggest it could have easily been more than that.