Random: Definition of Parallel Lives

Would you consider two people to be living parallel / mirrored lives…
Of happiness or sorrow or pain…
If they are the ones to put each other through it?

Or would the phrase ‘parallel lives’ seem more applicable….
If they did not contribute anything in any way to each other’s life and still have it similar?

Hmmm…

Just a random thought…
After reading some posts, for self amusement purposes.