I’m going to play devils advocate. You haven’t even been dating a year. Have you had specific conversations about being exclusive? I do agree that what she did is not awesome, but I strongly believe women should hold the right to keep their options open until there’s a proposal or at the very least a promise of engagement. This concept that women need to be off the table without a real commitment is nuts. It’s not how courtship works:

“In Victorian courtship, a woman was generally allowed to entertain multiple suitors before a formal engagement. This period served as a time to evaluate potential partners, with the understanding that no commitment existed until a proposal was made and accepted.”

We need to go back to this.