Maybe I'm just jaded from reading so many 'enemies to lovers' fics over the years, but a lot of Dramione stuff misses the mark on tension for me. They'll have Draco call Hermione a Mudblood in chapter one, then by chapter three they're sharing a heated look in the library because he secretly respects her intellect. That's not tension, that's whiplash.
The good ones, the truly hard-won pairings, make you doubt it'll ever work at all. It's not about smoothing over his prejudice, it's about him having to dismantle his entire worldview, brick by painful brick, while she's right there watching him sweat. Hermione's not waiting around for him to get better, either. She's got her own life, her own righteous anger. The tension comes from wondering if the cost of rebuilding him is something she'd ever be willing to pay, or if the man he becomes is someone she could even recognize, let alone love. The 'Princess of the Slytherins' or 'The Auction' kinda got this, where the external circumstances force them together, but the internal gulf feels miles wide for most of the story.
Honestly, the best tension I've seen lately isn't even romantic for the first half. It's professional. They're forced to work together post-war, maybe as Healer and Potions consultant, and every interaction is a minefield of past insults and present necessity. That slow, grudging respect that has to form before any flutter of attraction can even be acknowledged—that's the good stuff.