YTA, my dude. Traditions are something entirely different than altering one’s biology. This is an incredibly personal, permanent decision on her part. This isn’t like substituting cottage cheese for ricotta in lasagne, this is a whole PROCESS. No one should have to change their body at their partner’s request. I remember my late spouse forcing The Change on me; nothing I regret more than staying in that relationship.

And given that you mentioned she JUST found out, I’m seeing a totally uncool pattern of miscommunication here. You two need to open things up. Talk about expectations, culture, feelings, etc. Give her lots of time to make a measured decision. Don’t make her be your Bella. And maybe she didn’t really grasp that she’d be spending an eternity with you. You could want different things out of life.

No tradition is worth someone’s bodily autonomy. And maybe I’m assuming that this relationship has sane and consensual foundations, but if you can’t respect her decision, maybe you’re better off leaving the wedding canceled.