burned voltage regulator connection

[86 goldwing]

hi everyone just doing some work on my bike this weekend seeing how we are in a lockdown again and not supposed to go any where
thought this would be a good time to get my trailer hitch on
well it was not as easy as i thought it would be things had to be cut and re-drilled to fit but got it done
then came the hard part rewiring all my lights that took for ever so many wires again that is done
now for the interesting part
as i was doing the wires i found a wire that had been forced between the frame and the seat and had worn the insulation and sorting to ground right near the gas tank
so off came the seat and faux tank replaced said wire but got the first look at my voltage regulator
wish i hand not seen it because no more riding until i order a new one
the connector is all corroded wires are green and the plastic connector has melted
going to post a pic hopping someone can tell me why this has happened