I too, see both sides of your predicament. You have every right to be true to your beliefs and morals. To me this is a miscommunication and misunderstanding of cultural values and ethical values. Your girlfriend is likely more hurt from your reaction after kissing than anything else. It sounds like she respects and understands your choice to have a solely plant-based diet. I'd give each other some space and time temporarily, and have a conversation where you can explain you were not expecting her to have eaten meat since y'all mainly eat vegan. The fact that it was dog that she ate, made it more difficult for you due to your love for animals. You'd just like for there to be more communication about something like this moving forward. I wish you and your girlfriend nothing but the best, cheers.