Deleting implied relationships may delete the wrong relationships

Scenario: User 1 requests to be a Roommate of User 2, and User 2 accepts. Roommate implies Friend, so now there are two relationships, Roommate and Friend, where User 1 is the requester and User 2 is the requestee. If either one deletes the Friend relationship, all of User 1's Roommate relationships are deleted.

I have a fix, which I'll commit soon.