A couple that is so intertwined with each other's life that they never do anything without the other present. They act as if being torn apart from each other would cause physical damage to themselves such as with the Schistosoma parasite where the female is literally intertwined within the male.
Becky and her boyfriend are so schistosomial, ever since they have been dating, she has never left his side.
that couple you always see constantly in physical contact with each other. they always seem to be holding hands, playing with each other's hair, etc...