Pairings are changed all the time for various reasons. I don’t see any problem in the case you described, especially if it’s a smaller tournament. I wouldn’t expect a section of 200 players to be re-paired for something like this, but a small section sounds OK. (I also might not honor such a request in the last round of a tournament if prizes were at stake)
I’ve asked TDs not to pair me against somebody just because he lived near me (why drive hundreds of miles just to get paired against a nearby chess player that I can play any time). It’s up to the TD’s discretion whether to honor such requests. It usually depends on whether the request can be honored without causing a major disruption in the tournament. This case sounds pretty simple to me.
Most TDs will move players around to try to avoid certain situations, the most common probably being siblings playing each other in scholastic events. I’ve avoided pairing two players in an early round at their request because they drove 300 miles together to get to my event.
And, yes, I’ve done it after the pairings were posted.
But if it’s the last round or two, those pairings will usually stand.