I don't think these people believe that they're actually gay men inside. At least I don't think the majority of them does.

What they're doing is preserving their ego. This woman admits her infatuation with gay relationships has reached the point of obsession and she must feel at least a bit guilty about it. And so her brain does a 360 and goes "you know, if you actually were a gay man, you'd be totally justified in doing what you're doing".

Classic ego save. Very reminiscent of morbidly obese people finding some totally illogical excuse for being deathly fat (genetics, some rare disease, thick bones, "actually, you can be healthy at every size" etc.) because admitting you're wrong and changing your behavior accordingly is too hard.

Of course this isn't like the one and only reason for people acting like this but it is a major one imo that I don't see discussed so often.