I have a SQLite DB that is set up so when I delete a Person the delete is cascaded. This works fine when I manually delete a Person (all records that reference the PersonID
I just dealt with this exact issue. It turned out that when I used EF to Update model from database... option, it didn't properly get the "Cascade" rule for on delete.
Try going to your EF database model, click the association that is causing the problem, then make sure that the End1 OnDelete (could be End2, depends on database scheme) is set to Cascade.