I hold to neither doctrine and think I can help you make sense of this.
So what accounts for the differences in the accounts? Well, even though the subject of the discourse is prophetic, its recording is historical. In other words, this was not written down under prophetic inspiration by Jesus, but was inspired to be written down as a testimonial narrative by those who heard him (or by those that heard from those that heard him). As in the case of any event witnessed by different people, the individuals involved will be subjectively attentive to and impressed by different details and aspects of what objectively took place. These differences do not reflect error, contradiction or unreliability, but merely the individual perspective of the witnesses involved. God uses the individual’s experience, memory and communication skills to disperse reliable truth.
When parallel passages differ in level of detail reported, the one which reports finer detail is correct in that detail. The more general passage is not wrong, it just didn’t visit that detail to the same depth or at all. This is particularly seen in the disciples’ question to Jesus (Matt 24:3; Mark 13:4; Luke 21:7). Mark and Luke are about the same, whereas Matthew is very different. Matthew captures the gist of the question as put forth in Mark and Luke, but adds the significant detail, “and what will be the sign of your coming and the end of the age?” That detail is what makes sense of Jesus answer in all three reports, especially, given the history that has since unfolded.
As to the passage itself, we find Jesus and his disciples in Jerusalem at the Temple, taking in the sights, so to speak. Jesus prophesies that total destruction is coming to what they are looking at. When they are in private later at their site on the Mount of Olives, the disciples (at least, Peter, James, John and Andrew according to Mark 13:3) dare ask him a two-fold question: When? And what will be the sign of his coming and the end of the age? Mark and Luke’s account only capture the “when” and, in effect, skip the question about his coming and the end of the age.
His "coming" (parousias) is really the way of speaking of his arrival, of his being present here--not in an ethereal sense (as in, "lo, I am with you always, even to the end of the age”) but in a substantial one ("...while they were telling these things, He Himself stood in their midst"). Since he is standing with them at the time he is speaking these things, the implication is that they knew he would leave and then return to end the age, hence the link (kai) between his coming and the end of the age. My assumption is that they assumed that the destruction of Jerusalem would result in a new Messianic age.
So Jesus, basically, brushes off the question about the destruction of the Temple (it wasn’t important to the big question) and concentrates on the second question (which, really, was the big question)--when would he come and the age end? His response is focused on that question in all three accounts, but without Matthew’s account supplying the detail, this would not be clear. In fact, he never does deal with the first part of the question, and instead takes up Daniel’s desolation (Daniel 9:27; 12:11). To tell you the truth, the destruction of 70 CE was only, at best, a pretext to what he wanted to talk about, but in fact, doesn’t enter into the actual answer at all!