To shamelessly paraphrase a recent post from @will,
Browse this thread:
Poll thread: romantic interests
And take absolutely none of it as gospel and do your own thing anyway.
More seriously, in general I recommend coming up with characters you find interesting first. If players aren’t interested in getting spending time with characters initially, they won’t be interested in getting closer romantically either.
That said when someone writes a ChoiceScript game with a haplessly ambitious loser like Rhys in Tales from the Borderlands whom I can romance, I will be very happy.