Man, searching for that specific combo is like trying to find a dragon ball without a radar. Most DBZ lemons are... well, you know the drill—power level comparisons and not much else. The few that dig deeper usually aren't on the big sites. I once stumbled across a Future Trunks/Mai story set after Black's rampage that actually made me feel something. It was buried in an old LiveJournal community archive that someone had mirrored. Those old-school, character-focused writers from the early 2000s sometimes nailed the melancholy. Your best shot is using Wayback Machine to dig through dead forums; the signal-to-noise ratio is terrible, but the gems are there, hidden under mountains of cringe. You just have to be willing to wade through a lot of badly coded profile pages and broken image links.
It’s a specific, almost niche request within a niche. I wouldn’t bother with AO3 tags alone—too broad. Try searching for authors who also write serious, canon-compliant drama fics, then check their bookmarks or older works. Sometimes they wrote the emotional lemons as a side project years ago and never tagged them properly.