I hated that pairing. She was such a bitch. At least with Jessica you knew she was just using Bart, but Nikki can't make up her mind what the hell she wants. But as she's just a one-off character, probably never to be seen again (thank god), I don't have any more worries about her screwing Bart up in the future.
I'm just waiting for the moment when the writers actually have Bart and Sherri/Terri get together, even if it's only for one episode.
They've been throwing hints that there's an attraction between Bart and one of the Twins all through the series, ad it was implied that he actually went out with one of them to a school dance ("Hungry Hungry Homer" episode), but nothing has ever been shown of this.
But it'll probably never happen, as the writers are obsessed with cramming guest-stars into almost every episode these days, and that's an excuse to give Bart a new, never-seen-again love-interest each time.