I agree with both premises. "The one who got away" was never there for the times that can make or break a relationship. They did not get to prove that they could be the rock/support that the person may have needed when the word that rhymes with it hits the fan. So yes, they are a memory, but in truth they also could have been that person that would have helped the relationship to flourish. On the other hand, if a person is not ready for the responsibility (maturity, care and concern for another, sacrifice) that is required to form a lasting bond it doesn't matter if it's the one who got away or if it's the unfortunate person that got stuck with them, it's still not going to be a fully satisfying union.