POTD: Contingent relationships

The legend goes that if you place a lock here with your partner and keep one key each, then you’ll be together for as long as the lock is in place. Taking this at face value, there are a) contingent relationships, because there are locks on locks since the bridge railings are out of space (or maybe mistresses); b) polygamous/ polyandrous relationships, because I’m sure some locks come with multiple sets of keys, or foreigners misunderstood the instructions; c) relationships that ended quickly because of poor foundations, like those who bought cut price locks and had them rust away; and d) those which were forgotten because of misplaced keys. Malostranska, Prague, Leica M9-P and 28/2.8 ASPH.