Where after Molly dumps him Jim Moriarty realizes he's in love with Molly and starts to actively pursue her & when Sherlock finds out he's not happy especially since Jim totally starts to neglect his little game with Sherlock. Whether Sherlock is jealous cause he's in love with Molly but thinks it's a chemical defect would be brilliant. Honestly, I'd prefer if Molly eventually chooses Jim over Sherlock cause he may be a psychopath but at least he treats Molly with affection and because he just loves her with no ulterior motive unlike Sherlock