Final answer:
The riddle refers to a pair of objects that move in opposite directions but do so in coordination. The likely answer is feet or legs during walking, as they exhibit the described movement pattern.
Step-by-step explanation:
The riddle you've presented is a classic example of using language to describe a pair of objects or phenomena that share characteristics of movement. In the context of this riddle, the 'one goes forward one goes back' clue signifies a relationship where one object or concept moves in opposite directions relative to another. Considering the riddle's hint about coming and going together and the aspects of moving forward and backward, a possible answer could be feet or legs when walking. As you walk, your feet come together and go apart, one foot stepping forward while the other pushes back to propel you.