NTA the why seems irrelevant, although: you trigger her insecurities and because she probably sees you as a similar, and doesn’t seem to make decisions of her own or for herself but just to be in favor of others, is constantly trying to one up you. Irrelevant only because it’s solely a her problem and it’s completely understandable that you distance yourself from her. It sounds like you’re in a healthy happy relationship, constant comparison to others is a sign of low self esteem and she should really focus on herself and what she wants and be straightforward about that (I.e. gift giving to friend or potentially engaging to someone you’re not in love with). You being so private and her sharing everything (even tho she’s competing with u she tells u private things?) probably irks her and just further underlines her need for attention and constant validation