I would keep checking the online reservations before you go some slots may open up
If you cannot get the time or 2 top then yes go to the reservations desk (deck 5) when you board
Sorry to hear that some people are rude to a segment of our society not all Oceania cruisers are like that
We have had many enjoyable conversations/meals with same sex couples on O
Tuscan Steak is only on Sirena you may enjoy Toscana on the other ships
It also has a lot to do with the cooks ..with new staff they may not be fully trained by the sounds of things on Oceania's ways
Enjoy the cruise