Winter meant well when she said that she wanted Marcellus to fall for once.
That way, he wouldn't go around breaking hearts anymore. Even if he's only being a playboy for a whole different reason from a typical playboy, he'll definitely quit that once he finds someone he truly cherishes. He'll resort to other means instead because he'll be loyal to his beloved. What's more, he'll most probably change for the better.
With all that said, she does mean well. But then, for some reason, he turns back to being serious, which isn't really the reaction she's expecting.
"Say, Ms. Agreste..." Marcellus called out in a low, weak tone, confusing Winter for a little.
"What exactly do you mean by falling for someone? How would you even know that you did?"
Now, that's quite a problem.