I agree with all that has been said (especially the "parfait" metaphor!). If you feel you need to add a villain, perhaps it could be one that is antagonistic to both of your characters, a foe that they could work together to overcome or that would show them they have some commonality between them. It may divert from your intended plot, but it may also be a way to draw your characters more deeply. (Then they could discuss the outcome over some parfaits at the sweet shop.)