Myself, I've had this dilemma with the wife and told her where she could shove her family tickets. I wouldn't wear another jersey for anyone, and there are very few things I wouldn't stick to my guns for her, this is one of them. She even thinks that I should root for her Chargers and wear a jersey she bought me for xmas because I support her. That thing has sat in the same xmas box for 2 years now, never worn once. I won't wear an OU jersey/colors and I wont wear chargers gear just because that's what she wants. Funny that if the roles were reversed she says she'd wear an NU jersey, I call bullsh*t every time. She also knows i'd never ask her to do anything like that for me.
If this person is a true friend then they'd understand you sticking to your own morals and/or ethics. If not, so be it.