Lock and Load

Last spring I noticed an alarming number of padlocks sprouting on the Pont des Arts, the pedestrian bridge between the Louvre and the Institut de France.  They're still there, and they've been multiplying.  There are hundreds of them, in all shapes and sizes, some with names written on them, some fresh from the hardware store.  Now I see them on other bridges that have wire fencing they can be attached to.  What is all this about?

I gather this is the latest way to swear undying love for your mate: hook a padlock onto the bridge and throw the key into the river.  I suspect many of these romances end before the key floats very far downstream, leaving an ugly excresence as the only reminder of love's short stay.