My (21/M) gf (20/F) of over three years broke my trust the other day. I make the personal choice not to drink alcohol, but I don’t press my opinions on anyone else. With this being said, my gf and I had a serious conversation last fall about how it makes me uncomfortable if she were to drink at all before she is 21. I understand that underage drinking is very normal, and I am the outlier. She saw how upset I am about this topic though, made me a promise to not drink again before she turned 21, and she just told me yesterday that she broke that promise. She apologized for it and I can tell she feels bad, but at what point do you let go when someone breaks a promise? I tend to be forgiving by nature, so I have forgiven her but I am having trouble letting it go. I know drinking something is not as serious as something like cheating, but in a way it feels the same, because it was a simple and conscious choice to break the trust and loyalty of a relationship. She was with her friends who were drinking, and felt pressure to do it to, which makes me think that she cares more about her self-presentation to others than me and our relationship. Any thoughts would be appreciated.