I would guess other version. She is already dating and with only one admirer.

My guess (haven't heard of this one) is that it could refer to her being crazy; like her being in a straightjacket (the ones they use in a mental institution). In other words: forget her; she's locked up in a padded room somewhere for being completely cuckoo. :) (not necessarily literally in a straightjacket, but used metaphorically, to indicate she's loopy)