Okay so, I don't remember much of this manga but I remember it being about a girl who worked doing some sort of... break-up services. People who were dating someone but did not want to date that person anymore, but didn't have the heart or courage to end the relationships themselves, would contact her and the people she worked with and they would end the relationship for that person. I remember the main female character having either black or dark brown hair, most likely in a ponytail. I also think the main female character was based off of a real life female idol in Japan, I think it was someone from AKB48. But then again, I'm not sure if it was because the manga was actually based on a jdrama of the same name. It might have been.

Edit: I found it. xD It's Mielino Kashiwagi