verb. to cowardly end or avoid getting into a relationship by slowly (or quickly) phasing oneself out of the other's life.
More often done by males, although females are not immune.
"Dude, she was hot and all, but now she thinks I'm her boyfriend- I just wanted to hook up!"
"Dude, that sucks. What are you going to do?"
"It's time to unvolve, stat."