Come between (Affect negatively or cause discord between (someone) and another person)
Our love is so strong that nothing can come between us.
Come by (Obtain; to get, especially by chance or involuntarily)
A loyal friend is hard to come by.
Come by (Come near to; pass; visit)
Your beau came by while you were shopping.
Come down (Decrease)
Real estate prices have come down since the peak of the boom.
Come down upon (Criticise, reprimand severely)
They’re coming down heavily upon people for not paying their taxes.