Each has their own preferences, so choices matter a lot. That's not only during conversations, but also during waiting time between them and the occupation you've chosen. (Meaning, scenes play out differently / have different dialogue based on these types of things.) You have a few different combinations, though: Scholar, Warrior, and Scholarrior is only part of that. The ship you choose, responses during conversations, etc., all also affect how things play out. Right now, the ship you choose is one of the most important choices for obvious reasons.
That's at least true up to this point; I have no idea how long they will be on the ships — that travel was pretty slow that far back in history — but if they spend a lot more time actually in Vinland, you might still be able to develop something with the girl who was on the ship you didn't choose. Presumably, trying to do that won't work though, or at least it won't work as well. At a minimum you'll be missing out on the relationship growth that could have happened while sailing.
Personally, I don't think you're going to be able to have both. While it's true what Neimad says, at the same time I don't think it will work out for the reasons I explained above. But neither of us are the developer, so we can't answer with any certainty.