"You have a sad feeling for a moment, then it passes"
A poetic, bittersweet line. In a way, the sadness is the "good" part, when you feel the most longing for what's been lost. The real loss is forgetting.
replies(1):
"what is grief but love persevering?"
which kind of implies the sad inverse -- that once we pick ourselves up and carry on, it necessarily means that the love isn't persevering quite so hard.
It's certainly poetic, but I don't think it's accurate.