Son compartido

Am I The Asshole for refusing to give up my airplane seat after finding out the real reason they wanted it? I was on a six-hour flight last weekend and specifically paid extra for an aisle seat near the front because I’m 6’4” and being stuck in a middle seat for that long is actual torture for me. Boarding starts, everything’s normal, and I’m already seated when a woman and her teenage son stop next to my row. She smiles and says, “Hi, would you mind switching with my son so we can sit togeth