I think you can always say, “No.”
I was flying home from Beijing with my companion who had strategically secured, and paid extra for, two seats in the central 3-seat-across corridor, with extra legroom, so that there was a single seat empty between us. He had hoped the extra seat would stay open and we’d have the row to ourselves. If the airline did end up booking the seat, he’d ask to trade his more desirable aisle seat for the center seat next to me…an upgrade for the traveler squashed between two lovers. Smart guy.
It turned out that the seat between us wound up being the only empty seat on the otherwise full flight…a valuable commodity.
Of course, there was a couple who hadn’t planned ahead and wanted to switch with a single man who then asked my companion to move into the middle and he would take the end seat in our row.
I am a midwestern girl and would probably take snow boots off of my feet in a blizzard and give them to someone if they asked me, but my companion is a very direct man and when asked if he minded scooting over to accommodate, not because the seat had been booked, he replied, “Yes, I do mind. I’m sorry but doesn’t work for us.” I was inwardly mortified, but also very impressed with my companion and glad he held his ground.
The flight attendant understood my companion’s right to say, “No” and fixed the situation by moving the single person into business class (which is a helluva upgrade on a 14 hour flight from Beijing) and after a few “tsk tsk’s” from fellow passengers, we had a lovely flight, as did the single traveler willing to give up his seat and the couple who had asked him to switch in the first place.
There is absolutely room for consideration for accommodating travelers who prefer to sit together, but I agree that just as someone is entitled to ask for consideration, the respondent is entitled to either accept or decline depending on what will or won’t work for them.
I’m working on being okay with declining.