Precisely and exactly. A tuning fork produces sound as it resonates with the vibration caused when it's struck, right?

So does a soul, but that resonance is produced by itself. In concert with others, these wavelengths can resonate at certain degrees of compatibility. Dissonance can harm the soul as well as the body, while resonance serves to make them stronger.

Mutual respect, mutually relevant interests, and personality traits that go well together all contribute to effective compatibility, but just because two people are good friends doesn't necessarily mean they will have good soul resonance.