Maybe DunKalar has the right idea here. I do like the idea (minus the harem option

! Although Jealousy Scenes were great... Although now that's I'm committed from Loren 1, I'd feel terrible dating again), but I feel that it could anger people. Some (me included) take headcanon very seriously...
Or you could do it like a Harvest Moon game, in which you can get married. Once you get married in that game, you can trigger scenes between other characters (bachelors/bachelorettes you didn't marry). But you could choose whether or not to view the scene, and, if you don't, they don't get married.
I think, though, that sound like a lot of extra work. And, I think if it's done wrong (i.e. out of the player's hands) it's would be a huge issue. It's not like I wouldn't buy the game, but other games that did this (Mass Effect 3) really annoyed me. It was my biggest issue in the game, and I'm sure that there are others that wouldn't like "canon" couples that they don't support (or even clash with your couples... "What!? Amukiki is supposed to be dating Draco!? No, he's dating me!"... And I wouldn't like something like that to be considered canon, you know? If it's in the game, and it's the only couple for Draco, it's kinda implied to be what's supposed to happen, right? And that would anger AmukikixElenor fans (me!), AmukikixSaren fans, and SarenxDraco fans).