A condition a person acquires when he/she has had several terrible past relationships that have left them with severe emotional baggage. Because of this, any person that enters into a relationship with a person afflicted with SEES in the future must work through, or "fight", each issue caused by each ex before the two of them can be in a healthy partnership.
There do not necessarily have to be seven exes for SEES to apply. This condition could appear with as few as one ex, if the ex was especially terrible.
Based on the circumstances in "Scott Pilgrim vs. The World"
My boyfriend's been cheated on so many times that he has a hard time trusting anyone. I think those bitches he was with before gave him Seven Evil Exes Syndrome...