No doubt other languages will have a totally different equivalent for that Dutch saying.
It's about nothing else but promising something you know you can't deliver (aka "to lie"), and just to make the other person feel good.
Another great Dutch saying which is rather similar: "Veel beloven en weinig geven doet de gek in vreugde leven". (Promise a lot and don't give much, that will make the fool stay happy).
It made me think some more though, and I realised Apollo was moon not Sun, then it all became clear, because Shiva/Rudra is Apollo and he is a Moon God and of course, so is Diana, big time.
It was the Moon cult they bought into Europe. Juliet pleads with Romeo to not swear by the Moon, it's so false and untrustworthy.
It's all fitting into place now so much better. I couldn't figure out why the Sun would come in when the Sun seemed already such an ancient symbol for the Fryans.