Will you ditch your thesis partner?

gosh that is a hard call, I never had a thesis partner but I have worked on projects with people. Once I ended up doing all the work but that is only because the girl was learning disabled and I wanted the presentation done right. However there was another time when we had a group presentation. There were 4 of us in the presenting and one girl wasn't doing anything no matter how much we talked to her, so we went to the professor and told her we didn't feel it was right that she should benefit from our hard work. So the teacher graded her separately on the part of the presentation that she did.