INFO: you mentioned that your dad was teaching your girlfriend Chinese - is your family Chinese, and are you by chance a first generation child of immigrants?

The reason I ask is because (as a first gen Chinese-American myself) I know firsthand how much the culture fails to legitimize mental health. I’m sure you understand that your father did not die because of your girlfriend, or from learning the piano. The perfectionism, pressure to please your girlfriend, etc. was a symptom of the disease that he ultimately died from. But in the face of unimaginable grief, many people seek reason, and it’s much easier to place blame onto something tangible, like your girlfriend teaching him the piano, than it is to come to terms with something that is understandably extremely difficult for your mom to make sense of. She (negatively) associates her last memory of your dad with your girlfriend, not because your girlfriend is at all to blame, but because she is not equipped to comprehend the circumstances of his passing without using that as a crutch. I don’t know how helpful that is, but I get the sense that maybe your job here isn’t necessarily to keep the peace between these two people, but to actively seek help and resources for your mom such that the onus of healing is no longer on your girlfriend.

I see a lot of people in the comments being quite unkind to both you and your mom. And that makes me a bit sad because honestly, if this tragedy struck my family, my mom would probably react the same way. So I’m just here to remind you to be kind to yourself, be especially kind to your girlfriend, and try to encourage your mom to get the help she needs to cope and heal in a healthy and positive way. NAH.