There were no sex cards, but if memory serves you could "romance" Jaheira (while effectively standing on the still warm corpse of her husband), Aerie (I remember that being kind of fucked but it has been 20 years), Viconia, and one of the boring dudes.

The "romances" weren't particularly well written but... they honestly aren't much better these days. We mostly just, as a culture, have moved on from needing everything to be a storybook romance and understanding that sometimes you just need a bang. Which makes "romance" in games a hell of a lot easier.

But also, since BG2 (well, NWN), Bioware have basically made their entire thing "romance options" and so forth. Similar to how Obsidian and Owlcat decided the real culture war was Turn Based versus Real Time With Pause. And Larian realized that we could do all the environmental nonsense that was originally only an option for tabletop games with GMs who didn't know why you were asking when it last rained.