You gotta be silent in two situations

One:When you feel one can't understand your feelings from your words

Because then it won't matter what you say,even if you said everything you have on mind,probably he won't get it,that is why you need to be silent.

Two:When one can understand you without anywords.

Then words are pointless,they already get it,so don't ruin the moment by saying much

Brought to you with love by