In this it's more like
Step 1: Characters meet
Step 2: Guy drinks the girl's drool that she left on her desk
Step 3: Guy gets sick
Step 4: She comes and tells him he's lovesick and now he has to drink her drool every day.
Step 5: They become boyfriend/girlfriend and gradually learn a little bit about each other each day, with sexy results.
Step 7: Profit.