[threebyfate]

IMO, the silent treatment is used to avoid:

1. The drama of breakup which sometimes, surprisingly includes the back-arse thought of not wanting to hurt someone else.
2. It leaves the door open for future contact, in case they change their minds.
3. It's also used as a form of manipulation, whether punishment or trying to get someone to do what you want, since the one who breaks first, is perceived to "lose". In the latter scenario, it's a lose/lose situation.