I remember reading a yaoi manga about two coworkers, where one had never gone on a date, so the second one "teaches" him on how to dress properly and get a good haircut, how to go to a restaurant, but ends up falling in love with him. The virgin was an exercise fanatic, who had a set of weights in his apartment, a refrigerator stocked full only of health drinks, and was kind of nerdy in that after they had sex, it's revealed that he used to love to collect these figurines that you get with milkcaps.

Do you know the name or author of this story?

Renai Shinan!

This is it! Thank you. How did you know?