Does the lack of feeling of acceptance toward a suitor after repeatedly performing the Istikhara prayer mean that its conditions have not been met?

If you performed Istikhara with sincerity and felt a sense of unease towards the person, this might be a result of the Istikhara. However, the more common understanding is that the one who performs Istikhara proceeds with the matter, and if it is good, Allah will facilitate it, and if not, He will avert it. There is no sin upon you if you refuse to marry this person.