looking for adventure/romance where the female and male lead travelling together are a couple already. or example they could be on a quest or simply just running away
they aren't a couple from the beginning though, it's just convenient for both of them to be together, but read/watch it!
Kaitai Shinsho Zero well kind of fits, and kind of doesn't... they act like one, and each one has feelings for the other one but well, it's not really official... and there is other stuff...