Can rape occur even after consensual sex has begun

Can rape occur even after consensual sex has begun? What if the “suspect” is 25 and met the “victim” in a drinking establishment where she was drinking alcoholic beverages and the “suspect” later finds out that the “victim” was 15 years old? Do you think the “suspect” should be held responsible? Do you think our laws on sexual assault are unreasonable or just right? Why or why not? Give research to support your answer.