Seikimatsu Darling and Close the Last Door are a perfect match. Fluffy yaoi comedy and some rather rocky relationships form the theme for both titles. The setting in a working environment is also the same and there are plenty of jokes that will appeal to the yaoi fan as they mock the genre in a very light hearted way.
Seikimatsu Darling and Be-Boy both take a shot at creating a cute shounen-ai romance story. The first succeeds considerably better, adding plenty of comedy and cleverly undercutting some of the conventions of the genre while the first relies more on angst and improbable plot gimmicks, yet there is an affinity in both titles and enough to assure that fans of one should find something of interest in the other.