I don't feel it’s necessary to match a romantic partner even on deeply held fundamental ethics
What I do strongly care about is that they are a good person, living from a heartful place and attempting to live from love.
For me this is more of a "way of being" which I resonate with rather than necessarily which specific side of the fence they happen to be on in particular issues.
The reason I believe there can be a disconnect is we are hugely affected by our conditioning and so someone who has grown up being conditioned one way can still be a good person despite not having yet seen through their conditioning.
For example, I'm a vegan and genuinely think the animal product industry is the atrocity of our era which future generations will look back on and say "how were people ever okay with that?" just like we do with so many things we look back on in history.
With my last partner though, she was genuinely a very good person living her life from love but she also ate meat and dairy. While I think the action is wrong, since we live in a society where it is so overwhelmingly normalised I think we can be blinded by our conditioning just like I remember being prior to becoming vegan.
So in that regard, I would have the same approach in general, I'd care much more about their way of being than what family or cultural conditioning they grew up with and so what their current stance on any particular issue is.
Edit: It has been pointed out that what I'm caring about here is virtue ethics, so the title should say ethical or ideological "conclusions"