Well, I think the problem with a lot of the other teacher/student relationships might be the tension and pacing. You know going in that they have at least x amount of time before their relationship can be even remotely acceptable, but they're always pulling the same shenanigans as normal romances. If they're not straight up going to cross the line, you tend to know it, and it makes it feel like a waste of time watching them inch their toes towards that line and pull away repeatedly. On the other hand the romance in this one was such a slow burn that by the time either of them even confessed, it was in safe waters. They're just at the starting line now, after having gotten close like good friends or even comrades first. The romance here may have actually benefited a bit from not being the primary focus and just being a subplot.