While it is a very disturbing concept, there are reports of such incidents, albeit rare. Jealousy can be a factor. If one girl is jealous of another, whether it be over a relationship, popularity, or something else, in a moment of extreme emotion and lack of self - restraint, she may engage in such a heinous act. Additionally, a lack of understanding of the seriousness of sexual assault among some young people can contribute to these situations.
Yes, unfortunately there may be some 'girl raped by girl story' in real life. Sometimes it could be due to power imbalances within certain social groups or cliques. For example, a more dominant girl in a group might try to assert her power over a more vulnerable one in an unacceptable way. Also, misinformation about relationships and boundaries can play a role if girls haven't been properly educated about what is right and wrong in interactions.