What this means is that we're dealing with someone who learned who his real friends are, how being a jerk just because you can be is no way to live, how fickle fate is, how little money and the good life really have in common and how anyone willing to debate the point can do something unpleasant to themselves starting with the letter 'S'. It doesn't take a genius to see that someone who regrets a severe case of being Moneybags T McBonehead isn't going to react well when a female version of the snobby jerk he used to be (not to mention someone he remembers from that phase in his life) comes bounding along throwing her weight around. Unlike the others he's enlisted in keeping his walking disaster best friend from accidentally killing himself, he knows who the pretty brunette who's just made the scene is: a girl who's willing to date a boy she knows her father hates because as long as she's not a victim of it, there's nothing Ronnie 2.0 loves more than chaos and uproar. This means that we have to deal with Archie, Bringer of Chaos and Veronica, Lover of Train Wrecks.
He also has another reason to not want her around as such: parents who want their old lives back. We can probably look forward to his mom and dad trying to get him all presentable and such so that he can marry well and get the family back where they belong. This will not go well.