The perfect match does not exist.
It will only exist a pool of compatible persons, not more than that.
They can not promise a perfect match.
eHarmony is a 16+ years old obsolete site and a HOAX, based on a big scientific fraud, only sustained by big marketing budget.
The Big Five normative test used by eHarmony and EliteSingles/eDarling, had been proven/revealed as an incomplete and incorrect model to assess/measure personality of persons.
Very easy to copycat eHarmony, but very difficult to innovate: a 100 times better algorithm than eHarmony.
Please read: The 8 tips to innovate in the Online Dating Industry!