Visitor visa failure may or may not have an effect om Fiancee visa, we have know way og knowing as the embassy do not give away this info. This is one of the reasons we recommend not trying for one just in case it does have an effect, as to be honest you are either thinking of marriage or not, so why need a visitor visa? The finacee gives you a 6 months trial period, and this is the way the embassy think.
Most visitor failures are due to not proving she will return.
