Dreaming about a roller coaster ride seems to symbolize the emotional ups and downs that a person is experiencing. Although, this ride can be fun, it can also seem out-of-control and even be a frightening experience. As a dream symbols it suggests that the dreamer may need to achieve greater emotional balance.
The sever changes in mood and temperament are draining and unproductive and maybe highlighted by the roller coaster dream.
If the dream is feeling emotionally flat and apathetic, then this dream may be a form of compensation.... The Bedside Dream Dictionary
The roller coaster symbolizes the emotional ups and downs a person is experiencing. It indicates that great emotional ups and downs may be due to negative behaviors or thoughts (either your own or your partners). This dream may be telling you to exercise greater will and self control, and to try to achieve a balance in your life.... Tryskelion Dream Interpretation