i am not sure how it is on other ships but we were on the grandeur ots recently and there were several places we could sit alone as a couple.
our balcony
windjammer
pool deck
paladium theater (loveseat for two, if that counts as sitting alone)
any of the lounges, (schooner bar, south pacific lounge, singing in the rain , and viking crown lounge)
from what i recall, we did not make any special request.