[SWHouston]

AlwaysTexas,

I'm SO sorry to have to recommend the Re-Home, but, I sincerely think this is the only thing which will resolve this.
Just like humans, there are a few which are just psychologically unable of sharing the attention/place they once knew.

I'm thinking if you don't...
You're going to see a continuing separation between you/the family where he increasingly seeks out areas of solitude (like the bathroom) where he can morn his loss alone.
His appetite will start decreasing, and his health will suffer.
He may start angrily fighting back by attacking the Female and at last measures, passably you.

I know you think this is a medical issue, and yes, go ahead and get him checked out by your Vet, though I think that will be a waste of money.

PLEASE consider my resolution to this.

How proud you must be, to have him love you that much.