forbidden fruit is the sweetest

• the forbidden fruit tastes the sweetest

A reference to the story in the Bible in which God tells Adam and Eve not to eat the forbidden fruit, but they are tempted and do so anyway.

forbidden fruit is the sweetest

1. Forbidden things seem more appealing; people desire things more if (or, in some way, because) they can't have them.

• the grass is always greener
• the grass is always greener on the other side