Originally Posted by Jetée

Unless the girlfriend was listening in at the time, (or if both parties were present in the studio, which is less likely) he didn't dissolve their relationship in anything other than his mind. He'll need to do it again eventually so she gets what's going on, or he can go on avoiding her for no apparent reason, thinking his on-air message should have reached everyone, including his girl.

It's the "if a tree falls in a forest, yet no one is around..." principle.

You (the hypothetical breaker-upper) need to communicate such a thing to your partner, not to the disinterested audience that gets a few minutes to whoop it up, and then forget about it tomorrow.