Veganism is not a religion and we are not dogmatic. Your boyfriend is wrong. You made a mistake, so what. You are doing very well by being a vegan for six months. I have been a vegan for 16 years and a vegetarian for 29 years before that and very shortly after becoming vegan I saw some fake meats on sale at a very low price. They had egg whites in them. I purchased them and ate them. I have never done that again and have no intention to do it again. I am still a vegan and so are you.
One other thing: Almost every vegan has accidently eaten something that has flesh in it. We only found out later and probably sometime we never even knew that we accidently ate something with flesh, dairy, or eggs in it. Do not beat yourself up. Just keep up the good work. From a fellow vegan.