Nounai Renai no Susume

From Fantasy Shrine:

The ordinary Yu who works in a florist shop has an extraordinary secret—he has multiple personalities! His alter egos include the cool, level-headed elite lawyer, Kaname and the wild, rough body-builder, Ryo. Both are extremely protective of Yu. But Yu wants to date another man. How would his alter egos deal with this new development? Love and sex of 3 couples in a non-stop pursuit.