in Hibernate Users FAQ - Advanced Problems, written that:
This almost always happens because you forgot to remove a deleted instance from an association with cascading save enabled. You should remove deleted objects from associations before flushing the session. Basically, the object you're trying to delete would be resaved to the database by it being in a collection hanging off another object. You need to remove it from other collections before deleting it.

Are there any ways to force hibernate to break the association in such delete conditions?