good luck. My lady's family is from Boston and follows the Celtics closely. It's been a friendly thing until recently...
I've warned them that I can't mask my hatred for at least 2 years and (a) don't talk to me about it + (b) let me gloat brutally when we beat them + (c) handle it well when the whole team falls apart and I laugh while pointing fingers.
If I were you, I'd set up the same terms.
It could be way worse. She could be a Lakers fan.
I met the perfect woman the other day, or so I thought. Turns out she's from Boston and is a huge Celtics fan. Dealbreaker? I think it will be fun. I hope.