If you love something, let it go [...]"

I think it basically means that if you're having problems in a marriage, a relationship, or anything really, that you're supposed to let them go instead of trying to hold onto nothing. If things work out and they come back, it's meant to be. If they don't come back, it wasn't.

I actually was forced to do this recently. We came back to each other and are happier than ever.