The Golden Age of Greek literature preceded Alexander, and so obviously most of the renown authors would not have written anything about it. From Roman sources (and a couple Hellenistic writings) it's rather clear what the relationship was thought to have been, and the basic modern Greek counter-argument is that it's nothing more than hearsay. It's a fairly silly dispute which could be brought up about most any ancient records.
The Greeks just don't want to admit that their ancient forebears were mostly bisexual sluts..
"White folks was in the caves while we was building empires. We taught philosophy and astrology and mathematics before Socrates and them Greek homos ever got around to it."~Al Sharpton
There aren't that many records of the period.
The New Testament has thousands of times more documentary evidence, and it is controversial.
Imagine having a few late-dated manuscripts far removed from the time and making authoritative statements about the era in question, much less about an individual.
The Greeks just don't want to admit that their ancient forebears were mostly bisexual sluts..
The Roman 'Pot' Calls the Greek 'Kettle' Black! (Call the NYT!!) As if the Romans were paragons of virtue!