confused.

I saw a girl talking about how she and her boyfriend had had drunken sex and in the morning she said that she wish that she had not. Everyone in the comments was saying that he raped her. I don't understand. He was drunk as well, couldn't he just as easily say that she raped him? I know you are unable to give consent when under the influence, but if they both are, why is he the rapist? What if he woke up in the morning and he regretted it as well? Is he still the rapist? I don't understand!!