Personally, I believe it refers to "the end [singular] of the age [singular]" (yet future to occur) that is NOT a part of "this present age [singular]," but that immediately precedes "the age [singular] to come" which is the [their] promised and prophesied earthly Millennial Kingdom (what was promised to Israel). The disciples (at the time of their inquiry to Jesus in Matt24:3 [asking because He'd ALREADY spoken to them about it in Matt13:30,39,40,49-50 (when the angels will "REAP")]) had NO knowledge [at that time] of that which is known [presently] as "this present age [singular]," and no one today is preaching "the kingdom if the heavens IS AT HAND" like they did in the early parts of Jesus' earthly ministry (that ceased being said, at some point), and which is the equivalent of "the wedding FEAST/SUPPER" [i.e. the future earthly MK]; but instead is being conveyed that which pertains to "the MARRIAGE" itself, instead (2Cor11:2, etc).
[note how Eph2:7 speaks of "ages [plural] that are coming" from the point in time of "this present age [singular]"; and from their perspective (meaning the disciples who'd asked Him), just "the age [singular] to come [the (FUTURE) MK age]" ]