I'm friends with someone.  We had an off again, on again relationship for a while.  I haven't met anyone since then.  They have.  They're happy.  It's a poly thing, one of the reasons we never worked out.

I am happy for them. I am genuinely happy for them.  

But why do I feel so hurt, crummy and jealous?  Am I just a terrible person?  Is this a bipolar thing?  I always feel like an outsider.   Always have, probably always will at this point.

I don't know.  I need support, something.  Apologies if this is off topic.