I don't really care about romance options personally, but I'd argue that the below is wrong:

If the romances are supposed to be well written, the characters involved should have an actual defined sexuality.

If the romance/character is well-written, it should play well regardless of gender. If the NPC is interested in you because you have tits or a dick, it doesnt sound like a particularly well-written romantic plot.

Think about most good film romances, and imagine if they'd work with gay/lesbian couples, you'll find that most will. Sure there may be minor dialogue changes, but the actual content of their interactions shouldn't change.

The only way you pigeonhole an NPC as gay/straight is to plow full speed ahead into a bucket of stereotypes. That's not good writing, it's lazy.