mo are desho

A woman commits suicide after long-term depression; she's felt isolated and alone after moving from her childhood home. A friend goes to the hospital to identify the body, and the only permanent possession of hers he can retrieve is a ring she once wore. He later wears it on a chain around his neck, and a friend asks him about it.

「その指輪・・・・・」
He smiles bitterly and says: 「仲間はずれもアレでしょ。」

I know that "nakamahazure" means "left behind" or "ostracized", and the sentence seems to break down to "nakamahazure - also is - *that* - isn't/wouldn't it?". I can't figure out the total meaning of the sentence, though. I don't understand to what the "are" refers, as these are the first lines of the scene. I also don't understand to what the "nakamahazure" refers - the woman, the ring, or the act of being left behind itself? Is he making a comparison between the ring and his dead friend, saying that she was "left behind" as well (due to her insistence on living in the past)?

Thank you again.

The man is received the woman's ring, and he wears it on a chain around his neck from then.
Is it right?
I guess that he doesn't make her soul (mind ? ghost?) still feels lonely, so, if he usually wears the ring, maybe he can think usually that the woman is with him, not alone.
(The ring is a distribution of mementoes of her for him.
Japanese thinks there is the soul/mind/ghost of dead person in it for a while.)

仲間はずれもアレでしょ= It means, "I don't want to make her alone."

katakana "アレ" is slang that represents a negative opinion.(too cruel, too sad, too radical, not a good idea, etc.)

Thank you both very much. A question: what role does "mo" play in the sentence? Is it simply the usual role of "too" - as in, "It'd be a pity if she were left alone too (in addition to being dead)"? That seems rather callous to me in this situation. Am I reading the usage of "mo" here incorrectly?

This "mo" would be more like "(Something as far as) leaving her alone would be sad, right?" rather than "in addition to" kind of meaning.

Argh, can't believe I didn't catch that. Thanks.