When Jim Fitterling of Dow and Tim Cook of Apple step down as CEOs in July and September respectively, the Fortune 500 will lose two widely respected leaders who led their companies through transformational eras. The exits of the two men, who both identify as gay, will also mark a dispiriting step backward for LGBTQ+ representation in the C‑suite. After September, there will be only one out LGBTQ+ chief executive left in the Fortune 500: Land O…