“The only three men I had ever imagined a future with all told me that something was missing,” Oz Johnson wrote in her Modern Love essay. When Oz was 23, her boyfriend said she met 99 percent of his criteria, but she was missing 1 percent. Over a decade later, another man broke up with her via email. Their love was almost perfect, he said, but not enough to last.What is this missing, unquantifiable feeling? Oz used to be haunted by these rejections, but now she has come to embrace the search for imperfect love.After: Nancy Cardwell wasn’t looking for love — but then, at 58 years old, she fell passionately in love with tango. Her newfound zeal for the dance took her to Buenos Aires, where she fell in love again — this time, with a man named Luis.