"He whom thou lovest is ailing."
Now what would we understand this to mean if this had been a woman, and the message had been "The woman you love is ailing" ?
The woman you love. She whom thou lovest. I think this would have been understood through the ages to mean his girlfriend.
Well forget that Da Vinci code silliness. This is what the Bible actually says. It was a man.
And this seems to be happening in the last week or so before Jesus is crucified. So when the narration continues talking about the man that Jesus loved, it seems likely it would be the same man.
If that is the case, then the beloved disciple is Lazarus.
Remember there were 12 Apostles, but many disciples. Mary and Martha were disciples. There's no doubt that Lazarus was a disciple; he may have been the beloved disciple.
And the gospel of John itself is the testimony of the beloved disciple (whoever the beloved disciple was).
For me so far, this hypothesis seems to hold together pretty well. Most of what we have read in this gospel has been about Jesus's activities near Jerusalem. Lazarus would have known about these things first-hand if Jesus was staying with him at Bethany each time he came to Jerusalem for the feasts that we've been reading about.
But what about that wedding at Cana where he turned water into wine? Think about who told that story - we are hearing it in the voice of Jesus's mother. Jesus's mother lived with the beloved disciple after Jesus was crucified, so this is her own contribution.