In a similar circumstance, two weeks I was on a flight IAH - AUA, had paid for my first class ticket and selected seat 1E during the online purchase process.

During the coach boarding process, the FA approached me and said that a couple had not been able to get seats together and would I mind taking a window seat in the second row. I politely stated that I really prefered an aisle and wanted to stay where I was. She frowned & walked away, gathered the other FAs together and said loudly "That woman won't even change her seat so a husband & wife can sit together" and then they all turned around to look at me. Of course then the whispers began.

The same FA then moved on to coach and started asking other pax to switch seats to accomodate other couples.

I don't really remember ever witnessing this except in parent/child situations who had not been seated together.

Had I purchased coach and been upgraded, I probably would have swtched, being grateful for the upgrade. But I felt that I paid for first class, far enough in advance to get the seat of my choice -

Will be curious to hear your thoughts