Exegesis:

eleusaontai de hēmerai ‘but there will be days,’ introducing the announcement of some future significant event (cf. 17.22; 19.43; 23.29). Here the announcement itself follows in an independent sentence consisting of a temporal clause introduced by hotan, and a main clause in the future tense. hēmerai lit. ‘days’ means here ‘time,’ ‘period of time.’ The absence of the article is intentional.

hotan aparthē ap’ autōn ho numphios ‘when the bridegroom is taken away from them.’ The use of apairō may imply violence.

tote nēsteusousin en ekeinais tais hēmerais ‘then they will fast, in those days,’ double indication of time, the latter stressing tote. en ekeinais tais hēmerais intentionally recalls elusontai hēmerai of the first clause.

Translation:

The days will come when …, or, making explicit what is somehow suggested by the break in the sentence “but other days will come, and when…” (An American Translation, similarly Nieuwe Vertaling).

When…, and then … in those days, preferably, ‘(and) when…, then…, in those days.’ Often it is better to place the prepositional phrase closer to the word it is to stress, e.g. .’.. then, at that time, …’ (Willibrord); or indicating the stress otherwise, ‘at that time only…’ (Bahasa Indonesia). New English Bible shifts to co-ordination, cf. “but a time will come: the bridegroom will be taken…, and that will be the time for them to fast”.

The bridegroom is taken away. Where an active form is required the subject can best be ‘people,’ ‘enemies.’

From them, or, ‘from their side,’ ‘from their midst.’

In those days. Stylistically it is preferable when the rendering of “days” can echo that of the same word in the first clause.

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.