the grass is greener on the other side of the fence
Definition:  people are never satisfied with what they have, they often want to have more as they think that they will be better once they get that thing
Usage:  once we get what we want, we start to covet what others have because the grass will always look greener on the other side of the fence

SEPEDI
Translation:  bjang ke bjo botala ka lehlakoreng le lengwe la legora
Proverb: lešaka la pelo ga le tlale

XITSONGA
Translation:  byanyi i bya rihlaza ngopfu etlhelweni lerin’wana ra khumbi
Proverb: tihomu ta makhelwana ti nonile ku tlula ta mina

TSHIVENḒA
Translation:  hatsi ho dalafhala seli na luḽa ha mukaṋo
Proverb: munyadzatsimu yawe ndi mulima ya muṅwe