To see this as a 'gay' play is incredibly anachronistic and actually doesn't do justice to the sophisticated and complex arguments at work in this text. Not just did the idea of homosexuality as a sexual identity not exist in Marlowe's time (although sexual acts between men, of course, did) but the very borders between male intimate friendship, which might frequently involve sharing a bed, and a male-male sexual relationship were very fluid and almost impossible to determine.
What makes Marlowe's play so challenging is the way in which possible sexual and political transgression are inextricably linked: and the text itself probes the way in which Edward II's detractors are themselves guilty of precisely the 'over-reaching' of which they accuse the king himself.
To understand the sexual context of this play, it is worth reading Montaigne's essay 'On affectionate relationships' (in
The Complete Essays) where the most fevered, passionate relationships are not those between men and women, but between men, even though they are not sexual. The idea, especially, of male friends "seeking each other before we set eyes on each other... and so bound together that from then on none was so close as each was to the other" is one which culturally we no longer recognise, saving that kind of romantic diction for sexual relationships rather than non-sexual.
Commenting obliquely on favouritism at the Tudor court (Henry VIII's wives and their families; Elizabeth's favourites such as Leicester and Essex) and the way in which the personal life of the monarch might impact on his/her public life as ruler, this is a far more political play than an initial reading might support.
It is easy to read this as the product of a 'homosexual' playwright but there is no evidence that Marlowe fits this modern category more than any other Renaissance writer who eroticised the young, male body - as Shakespeare did in the 'fair youth' sonnets, for example.
Certainly the relationship between Edward and Gaveston is at the centre of this play - but to limit it to a 'gay' love story ahead of its time is to do a disservice both to the complexity of Marlowe's vision, and to the text itself.