YOU SAID:
your dad left to get the milk...but never came back
INTO JAPANESE
お父さんはミルクを取りに行ったが、戻ってこなかった
BACK INTO ENGLISH
Dad went for milk but didn't come back
INTO JAPANESE
お父さんは牛乳を買いに行ったが、戻ってこなかった
BACK INTO ENGLISH
Dad went to buy milk but didn't come back
INTO JAPANESE
お父さんは牛乳を買いに行きましたが、戻ってきませんでした
BACK INTO ENGLISH
Dad went to buy milk but did not come back
INTO JAPANESE
お父さんは牛乳を買いに行ったが、戻ってこなかった
BACK INTO ENGLISH
Dad went to buy milk but didn't come back
INTO JAPANESE
お父さんは牛乳を買いに行きましたが、戻ってきませんでした
BACK INTO ENGLISH
Dad went to buy milk but did not come back
it is unlikely that this phrase will ever reach equilibrium
