“ወደ ቸኮሌት ሲመጣ መቋቋም ከንቱ ነው።”

It means, when sth that is very good to extend it is believed to be too good to be good, trying to prevent that good thing from spreading is pointless/ useless. Here a chocolate is used as a symbol of a very good thing.

Do you want the literal meaning of these words or...?

It means if you already lost something.....there's no point of fighting for it......just give up