Was it never intended for Geordi's relationship in Typhon 4 to be long term. It seemed to me they were setting him up for something significant and then IFM puts him with Leah and Geordi feels the prior relationship was doomed.
It's not like there's some overarching master plan here, even when we don't have the kind of editorial shuffle we've had over the past few years. Most of the ideas originate with the novelists. Sometimes one author will introduce something into the mix that future authors may pick up on if they so desire, but sometimes later authors will have different ideas and choose not to pick up on those things. In this case, it just so happened that the author of the next TNG novel after Paths of Disharmony
had his own plans for a Geordi romance that required cutting the thing with Tamala Harstad short. If that hadn't been the case, that relationship might've gone on longer. It's just the luck of the draw.