You're changing, it's shaking up her status quo, she can't control it, and it's freaking her out.
Also, she's involved with another man/men so her sad little cricket is just dyin' to find something radically wrong with you to justify herself.
The self-examination is all well and good in the long run regardless, but remember her allegations may have exactly zero relevance to any sane perception of you before you devote much time to learning how to kill large animals with your bare hands or anything.
Also, a REAL man cares about manifesting masculinity in ways that seems authentic to *him*, not anyone else. IMHO.
"Show me a completely smooth operation and I'll show you someone who's covering mistakes. Real boats rock." -- Frank Herbert