But it did and it was very controversial to say the least. You seem to have forgotten the angry shipper wars between the Clois fans and the SM/WW fans during this period, that disproves your belief it wasn't unpopular. Ascended's point also fits in with how little communication there was between the Superman and Wonder Woman creators. Azzarello ignored it during his run which ran for over 30 issues uninterrupted and Johns didn't bother with the romance he introduced in his Superman run outside of a single panel where Diana is unavailable during Clark's call to her. So they're not falsehoods at all, it was a disastrous failure solely introduced to generate 'water cooler talk' in Lee and Johns' words, good and bad.
So the romantic dynamics jumping around after Soule left, the lack of continuity in Superman and Wonder Woman's solo series and the relationship swiftly deteriorating isn't enough proof that SM/WW was uneven and DC had no idea how to make them work as a couple. Let alone last as long as Superman/Lois Lane or any other iconic comic book romance.
Enough problems came up in the 4 years it lasted between the angry shippers, inconsistent writing and a lack of interest to make this relationship last resulting in a return to the previous status quo.